: Year 2000 Northstar 32V engine oil consumption problem?



Midnight LS1
01-05-04, 03:37 AM
Hi,
My mother has a 2000 Caddy Deville (limo optioned I believe, has two mirrors with lights that fold down from the top and as per dealer info which car was ordered by a limo company but backed out of the deal, dealer gave a great deal and it was in the month of December 2000)

Ever since it was new (about 13 miles on it when picked up) and after it's first few free oil changes from the dealer and GM, I noticed it has been eating oil a little bit.
Whatever the dealer put in, I don't know what brand and type.

After that, it's been quaker state 5W-30 (brother works at a auto parts store and brings home mostly quaker state brand as he gets big cases of them)

I'm a bit suprised it takes 8 quarts of oil for a change, i almost complained "how much more oil is this (bleep) gonna take".

Until then I started an maintenance log of all the vehicles (I maintain all the vehicles in the family)

Here's the latest:
Oil Change at: 42,262 miles
Oil level checkup: 45,327 - 1 quart added
Oil level checkup: 47,434 - 3 quarts added

The 3 quarts required to top it off did alarm me.
For the past time, I was trying to find out if the Northstar 32V engine built in 2000 did have a oil consumption problem or something's not right.

Is there any solution or TSB from GM on this?

ellisss
01-05-04, 04:15 AM
Hi,
My mother has a 2000 Caddy Deville ... Ever since it was new (about 13 miles on it when picked up) and after it's first few free oil changes from the dealer and GM, I noticed it has been eating oil a little bit...
Oil Change at: 42,262 miles
Oil level checkup: 45,327 - 1 quart added
Oil level checkup: 47,434 - 3 quarts added
... Is there any solution or TSB from GM on this?
1. check for an oil leak. The aluminum Northstar block is composed of four seperate sections. Block, lower bearing cradle, oil manifold, and oil pan. Both poor OEM sealing techniques and the inherent ability of aluminum to expand and contract when heated and cooled can cause oil to leak from the various seams on the assembly. There is a TSB for block re-sealing on the Northstar... and if the block is leaking while the car is under it's 3/36 warranty, then it will most probably be covered. It will also probably be covered if you have one of the higher-level GM extended warranties (not an aftermarket one, though).

If there isn't any oil leaking externally (and there shouldn't be), then...

2. The oil control rings (and their respective grooves on the pistons) have become contaminated with carbon. This is another issue with Northstar engines before 2003. There is a TSB and corresponding service procedure (that isn't covered under any kind of warranty) to deal with this. It entails soaking all 8 cylinders with a special solvent, then evacuating each cylinder. It's a rather expensive and time-consuming service (should be around $300-$400).

All of this is, of course, assuming there are no obvious problems... like a hole in a piston, or you overfilling the crankcase, etc.

--
Ellisss

JimD
01-05-04, 07:03 AM
LS1:

You are overfilling the crankcase with 8 qts.; the capacity is 7.5 qts. and the extra 1/2 qt. will be quickly beat to froth and sucked through the PCV system. Many Northstar owners use only 7 qts. for an oil & filter change.

When checking oil level between changes, remember the dipstick is calibrated for HOT oil. Again, many Northstar owners file a notch on the edge of the dipstick for a COLD ADD reference mark. And this Northstar owner does not add oil until the level is down more than one quart (there is plenty of reserve capacity in there).

Periodic spirited driving will help keep the top rings free to rotate. With gear selector in "2" from a stop, accelerate wide-open-throttle to 70+ MPH letting the computer manage the 1-2 shift. Leaving gear selector in "2", let the car compression brake back down to a crawl. Repeat. The brown cloud you see in the mirror is the carbon that used to be in the combustion chamber.

Have your Mom park over a piece of cardboard (or?) for a week so you can see how much oil might be dripping overnight.

Jim

ellisss
01-05-04, 12:01 PM
LS1:

You are overfilling the crankcase with 8 qts.; the capacity is 7.5 qts. and the extra 1/2 qt. will be quickly beat to froth and sucked through the PCV system. Many Northstar owners use only 7 qts. for an oil & filter change.
Jim, an 8 quart fill is perfectly fine. The Northstar is baffled beautifully, and I can assure you that an 8 quart fill leaves the level considerably below them.


Periodic spirited driving will help keep the top rings free to rotate.
True, but it's the _bottom_ ring that is solely responsible for oil control. When carbon saturates the third ring and it's groove, there is no efficient scraping of oil away from the cylinder wall.

The rest of your post was spot-on, though.

--
Ellisss

ellisss
01-05-04, 12:09 PM
Jim, an 8 quart fill is perfectly fine. The Northstar is baffled beautifully, and I can assure you that an 8 quart fill leaves the level considerably below them.

Replying to myself here... :)

Let's assume that I'm a goofy dummy who's all talk, and I'm wrong about what I said...

Your 'PCV system sucking it up' theory (while possibly completely valid in another situation) would only account for less than a quart of oil loss on the Cadillac in question. Where did/do the other two quarts go... through the PCV valve?

:lildevil:

--
Ellisss

Midnight LS1
01-05-04, 09:47 PM
1. check for an oil leak. The aluminum Northstar block is composed of four seperate sections. Block, lower bearing cradle, oil manifold, and oil pan. Both poor OEM sealing techniques and the inherent ability of aluminum to expand and contract when heated and cooled can cause oil to leak from the various seams on the assembly. There is a TSB for block re-sealing on the Northstar... and if the block is leaking while the car is under it's 3/36 warranty, then it will most probably be covered. It will also probably be covered if you have one of the higher-level GM extended warranties (not an aftermarket one, though).

If there isn't any oil leaking externally (and there shouldn't be), then...

When I put the caddy on the ramps, I do see a seeping like on the driver's side of the engine/transmission. I believe it's oil since its a very light brown color and it appears that it occurs when the engine has been running at or above operating temp for a short while. I cannot see any leak, must be less oil to cause seeping when the engine is hot but not when it's cold.

The caddy has about 47,500 miles now and it was purchased in december 2000 so i don't think it's under warrenty anymore.

Do you know the TSB #?


2. The oil control rings (and their respective grooves on the pistons) have become contaminated with carbon. This is another issue with Northstar engines before 2003. There is a TSB and corresponding service procedure (that isn't covered under any kind of warranty) to deal with this. It entails soaking all 8 cylinders with a special solvent, then evacuating each cylinder. It's a rather expensive and time-consuming service (should be around $300-$400).
I do know the "special solvent", it's GM TOP ENGINE CLEANER which is poured into the engine to clean out the carbon in the valves and the top of the piston and it costs about $10-15 a can which 2 cans are required. It's done by pouring it into an vaccum line carefully not to stall the engine. When the second can is put in, it should be poured enough to stall out the engine and let it sit overnight like that. Upon starting it, alot of smoke should come out, if not, drive it and do a few WOT runs which excessive smoke should come out. Then time for a oil change and replace the spark plugs.

the LS1 commuity use this method to fix pinging and knocking in some cases ;)

Midnight LS1
01-05-04, 09:53 PM
LS1:

You are overfilling the crankcase with 8 qts.; the capacity is 7.5 qts. and the extra 1/2 qt. will be quickly beat to froth and sucked through the PCV system. Many Northstar owners use only 7 qts. for an oil & filter change.

When checking oil level between changes, remember the dipstick is calibrated for HOT oil. Again, many Northstar owners file a notch on the edge of the dipstick for a COLD ADD reference mark. And this Northstar owner does not add oil until the level is down more than one quart (there is plenty of reserve capacity in there).

Periodic spirited driving will help keep the top rings free to rotate. With gear selector in "2" from a stop, accelerate wide-open-throttle to 70+ MPH letting the computer manage the 1-2 shift. Leaving gear selector in "2", let the car compression brake back down to a crawl. Repeat. The brown cloud you see in the mirror is the carbon that used to be in the combustion chamber.

Have your Mom park over a piece of cardboard (or?) for a week so you can see how much oil might be dripping overnight.

Jim
I do check the engine oil a few mins after it's been shut down from operating temp.

I'll try the sprinted driving method next time i get it on the road :lildevil:

The caddy was parked in the garage on a clean rubber floormat and there is no leaking found at all other than exhaust condesnation which is in the rear of the car.

Midnight LS1
01-05-04, 09:55 PM
Replying to myself here... :)

Let's assume that I'm a goofy dummy who's all talk, and I'm wrong about what I said...

Your 'PCV system sucking it up' theory (while possibly completely valid in another situation) would only account for less than a quart of oil loss on the Cadillac in question. Where did/do the other two quarts go... through the PCV valve?

:lildevil:

--
Ellisss
On my LS1 engine, I have an oil catch tank for the PCV system for this reason.

Brett
01-08-04, 06:09 PM
Do you know the TSB #?


This is what i can find on alldata

01-06-01-011A JUL 03 Engine - Oil Consumption Information
02-06-01-009B APR 03 Engine - Excessive Oil Consumption


Dont know what they say, but maybe helpful, Good Luck

97 concours
01-10-04, 01:57 PM
I have owned 3 Cadillacs with Northstars. And I have come to the conclusion that they all consume a bit of oil. It all depends on how hard it's driven as to how much you'll lose. I have a couple of friends that also own caddys with Northstars and they consume as well. We race them from time to time, sometimes all the way up the the speed limiter 130 mph for the Concours and about 150 for the STS with the Z rated option.

One note, if your flogging it pretty good I would highly recommend running a thicker oil. My preference is Mobil 1 15w50. You'll still notice some oil consumption, but it will be less.

Midnight LS1
01-19-04, 02:15 PM
I brought the caddy in to the local dealership because it was leaking coolant on the driver's side of the engine, since it's being cold out and I don't have much time to look at the problem and fix it with the downtime of ordering parts.

I brought it to the local dealer on friday (only free time I had) and they were too busy to work on it so i left it with them over the weekend, then they looked at it and said they ran a check and found 2 crankshaft position sensors needed to be repalaced (SES light comes on once in a while)
They only have one in stock and it took them a week to get the other one in.

Then they fixed the leaking problem which was a waterpump gasket.

It was ready at 4:30pm the next friday.

The car has 47,000+ miles and it's a 2000 and they covered it under warrenty :hmm:

So not questioning them, i took the repair statement and left :canttalk:

They must have put in the warrenty by accident :eyebrow:

Midnight LS1
01-19-04, 02:19 PM
I have owned 3 Cadillacs with Northstars. And I have come to the conclusion that they all consume a bit of oil. It all depends on how hard it's driven as to how much you'll lose. I have a couple of friends that also own caddys with Northstars and they consume as well. We race them from time to time, sometimes all the way up the the speed limiter 130 mph for the Concours and about 150 for the STS with the Z rated option.

One note, if your flogging it pretty good I would highly recommend running a thicker oil. My preference is Mobil 1 15w50. You'll still notice some oil consumption, but it will be less.
I use 5W-30 in the late fall to full winter season.
Then 10W-30 in the mid spring to mid fall season.

Crovax Z26
01-19-04, 09:01 PM
Gm says it is totally acceptable for these engine to burn 1 quart overy 2k miles.
8 quarts is the correct amount of oil
these engine do have a bit of a problem leaking oil and do require reseals , if it gets bad enough.
The procedure to remove this carbon off the top of the pistons is decarbing, you have p to put it in and let it sit for three hours, and then suck all the stuff out. this will alleviate the problem of engine knocking, and oil burning but will not stop it. the cause is in defective piston rings. this has been addressed and new rings are available. we tend to do 2 de-carbs on vehicles before we do ring jobs. your local dealer may do some thing different. check with them to see what they do

BeelzeBob
01-19-04, 10:44 PM
The correct oil fill level for the Northstar engine is 7.5 quarts with a dry filter.

7.0 quarts in the sump.

8.0 at a change is overfilling it and the oil exceeding 7 quarts in the sump will get aerated and cause excessive loss out the PCV.


The 2000 and later engine had hard anodized top ring lands in the pistons. On some engines so little load is placed on the rings (due to low RPM and gentle driving) that the rings never break-in the side surfaces of the hard anodized ring lands exacerbating the oil consumption. In cases like this a deliberate break-in schdule of full throttle alternating with heavy engine braking will help to break in the top rings. The easiest and quickest way to do this is to drive in manual 2 gear on the expressway at 60 MPH or so. WOT to 6000 RPM (about 75) and then lift off the throttle and allow engine braking to slow the car to 55 or so...then WOT to 6000 and lift off again. Do this 20 times or so and then shift to drive and drive normally to cool things off. Repeat the 20 WOT cycles several times. This will seat the rings into the side of the ring lands and usually helps oil consumption on the 2000 and later engines.

It is a good idea to do the measured 7.5 quart fill with a dry filter and check the oil dipstick markings for accuracy. Fill with 7.5 quarts and a dry filter. This should be at the full mark with HOT oil. If you check it cold it will be about 0.5 quart low...leading to the myth of the 8 quart fill. It is designed to be checked hot as per the owners manual and service manual and service bulletins.

BeelzeBob
01-19-04, 10:50 PM
I do know the "special solvent", it's GM TOP ENGINE CLEANER which is poured into the engine to clean out the carbon in the valves and the top of the piston and it costs about $10-15 a can which 2 cans are required. It's done by pouring it into an vaccum line carefully not to stall the engine. When the second can is put in, it should be poured enough to stall out the engine and let it sit overnight like that. Upon starting it, alot of smoke should come out, if not, drive it and do a few WOT runs which excessive smoke should come out. Then time for a oil change and replace the spark plugs.

the LS1 commuity use this method to fix pinging and knocking in some cases ;)

Actaully, that is one procedure with the Top Engine Cleaner that is often used.

What is being referred to , though, is the procedure where all the plugs are pulled and a solvent is pumped into each cylinder and allowed to soak into the ring lands for several hours. The solvent is then pumped out (so as to not hydrostatically lock the engine), the plugs reinstalled, the oil changed (copious amounts of the solvent will get into the oil so it has to be changed before starting) and then the engine is started and driven. "Spirited driving" is recommended to clean the carbon out of the chambers and to start to exercise the rings to get them moving and eliminate the carbon from sticking the rings in the ring grooves.

BeelzeBob
01-19-04, 10:52 PM
I use 5W-30 in the late fall to full winter season.
Then 10W-30 in the mid spring to mid fall season.
The recommended oil for the 2000 and later Northstars is 5W30. That is what should be used year round.

ellisss
01-28-04, 01:58 AM
8.0 at a change is overfilling it and the oil exceeding 7 quarts in the sump will get aerated and cause excessive loss out the PCV.
Oh, man... that is so wrong. :cookoo:

When was the last time you looked inside a Northstar oil pan? Better yet, when was the last time you changed the oil in one?

8 quarts fills the pan to aproximately 1/2" below the baffeling. I measured it.


The 2000 and later engine had hard anodized top ring lands in the pistons. On some engines so little load is placed on the rings (due to low RPM and gentle driving) that the rings never break-in the side surfaces of the hard anodized ring lands exacerbating the oil consumption.
I'm wondering where you get your info from. Do you really think/believe that the lionshare of oil comsumption is caused by that? No, you can't.

::sigh:: While carbon accumulation in the first groove is definitely a problem, it's the failure of the third ring (the one that's actually called 'the oil control ring') that is at fault. The first ring can be virtually perfectly sealed on it's sliding surfaces, and a 3rd ring failure due to carbon accumulation will still cause excessive oil consumption.


In cases like this a deliberate break-in schdule of full throttle alternating with heavy engine braking will help to break in the top rings. The easiest and quickest way to do this is to drive in manual 2 gear on the expressway at 60 MPH or so. WOT to 6000 RPM (about 75) and then lift off the throttle and allow engine braking to slow the car to 55 or so...then WOT to 6000 and lift off again. Do this 20 times or so and then shift to drive and drive normally to cool things off. Repeat the 20 WOT cycles several times. This will seat the rings into the side of the ring lands and usually helps oil consumption on the 2000 and later engines.
I apologize for quoting the entire paragraph... but I want to preserve it. I don't know what's funnier... you thinking that the Northstar's oil consumption problems are caused by the 1st compression ring... or that you think the pressure exerted on that ring by light-to-moderate driving conditions is light... or your fix for it.

--
Ellisss.

BeelzeBob
01-28-04, 02:52 PM
Ellissss....I hate to keep quoting and requoting all of your posts so I will just try and address the issues you bring up.

OIL LEVEL

When is the last time I looked into a Northstar oil pan....????....LOL...I helped design the SOB. Those "beautiful" baffles and drainbacks are all part of the design and development of the lube system done early on by....engineers....

Having worked on the Northstar engine since before it was lines on the paper and having DONE the oil level and oil starvation testing on the prototype engines I can assure you that 7 quarts is the correct oil level for the sump. 7.5 quarts is the correct fill level for an oil change with a dry filter. You are not correct no matter how you try to justify it. If you can explain to me the errors in the oil consumption vs. oil level testing, PCV system performance testing and blowby and the oil starvation work that was done on the tipping fixture and high G skidpad and racetrack work then I will start to discuss it with you. Otherwise, you are just speaking from ignorance. Period. The engine was tested and developed for a 1 G lateral acceleration with no starvation or aeration in a transverse mounted system.

Just so you are aware, there is much more to determining the oil fill level than measuring the height of the baffles in the pan and sump. There is a great deal of air motion in the crankcase (what engineers refer to as windage) and the moment of the air around the bulkheads and windage tray and such does a lot to determine how much oil can be in the sump and what the level is. The Northstar is sensitive (as are most engines) to overfilling and the sump, at the recommended 7.0 quart fill, is right at the limit of capacity.

There is a lot of proven oil consumption cases caused by repeated overfilling and topping off to the eight quart level. Use 7.0 quarts for the sump and you will be correct.

RINGS

I don't know how development work you have done on piston rings but you should know that ALL the rings contribute to the oil consumption and oil control. The bottom rings (the oil rails) are typically credited with doing all the oil control but they are not the only factor by a long shot. If you lookd carefully at the second ring on the 93-96 Northstars you will notice that it is a notched or stepped land ring.....wonder why....oil control, lad. The top rings play a significant, if lesser, part also. If the bottom rings are taking care of 99% of the oil then there is still a small amount on the walls that the top ring needs for lubrication and controls from entering the chamber. That 1% may seem small, but, over the long haul, can account for significant oil consumption if the ring does not control it. The 2000 and later Northstar engines have hard anodized top ring lands for wear and poundout protection. This is a good thing. But, looking at hard anodizing under a microscope, you will see that the surface is left with small "mounds" or a microscopic roughness. The side of the ring has to break in to this, or burnish the little microscopic mounds in the anodizing, to seal. If the engine is run moderately hard the gas pressure loads will seat the rings to the side of the ring lands and eliminate the minute leakage past the surface imperfections. Those same surface imperfections will allow oil past and into the combustion chamber leading to an oil consumption complaint. End of story. That is how it works. There are a lot of 2000 and later Northstar engines that improve oil consumption remarkably by being "whipped" to break in the rings...or use the procedure outlined above. That is the quickest and easiest way to subject the top rings to a regime of gas pressure loading and ring motion by loading and overrunning the engine. You're arguing with the wrong guy...I have done it to too many cars and proved that it works time and time again. There are also a number of other people that have taken my advice and improved their oil consumption on a late model Northstar. I have personally seen a field return engine (brought back for an oil consumption analysis) disassembled and viewed the ring lands under a microscope. The rings had never even been loaded enough to break in against the lands. Re-assembled and whipped, the engine easily was in the 4-5000 mile per quart range....just where it should be. You cannot stop all the oil at the bottom oil rails. The top rings will starve for lubrication and will microweld and fail. Been there, done that and seen it happen.

Yes, the gas pressure loads on the top rings in normal, day to day driving are pretty low. I have done ring wear studies at different gas pressure loads and can assure you that idling and driving at part throttle do verty little to load the rings. Asside from high loads at full throttle the rings actually rotate on the pistons at high speed. This is good as it keeps the rings "exercised" and free and helps seat them in the ring grooves. Years ago, GM did an intensive investigation into this phenomenon by putting a radiometric tracer on part of the ring and then measuring the ring position on the piston while the engine was running by basically using the output from a geiger counter mounted on the outside of the block. The most amazing finding from this study was that with any given ring and piston combination the rings will actually rotate at a measureable RPM at certain speed/load points. So, there is no doubt that the rings rotate and move about under load and RPM. If the engine never sees a full throttle, 6500 RPM upshift, then the rings will remain sedentary and be much more susceptible to carbon buildup and sticking.



One point for the future. Asking questions is fair. Saying you don't agree is fair. Being skeptical and asking for an explaination is fair. You don't need to try and be funny and smart and make trite comments. It just makes you look stupider when you are wrong.

El Dobro
01-28-04, 10:29 PM
Hey bbob,
Quick question. You mentioned the rings in the 93-96 Northstars and the ones in the 2000+ Northstars. Is the something different in the 97-99 years?

My 93 never needs oil added between changes but the 98 is another story.

BeelzeBob
01-28-04, 10:47 PM
Hey bbob,
Quick question. You mentioned the rings in the 93-96 Northstars and the ones in the 2000+ Northstars. Is the something different in the 97-99 years?

My 93 never needs oil added between changes but the 98 is another story.
I would have to get my notes out on that one....there were several interim ring package changes made in the 96 and later time frame. I think the rings were made thinner for better conformability around 96 or 97....I don't remember. About that same time the cylinder wall suface finish was changed slightly to a less agressive plateau hone and the rings were made narrower for better flexibility. I will check with the piston/ring engineer. Honestly, I have just forgotten all the little changes like that over the years.

The 93/94/95 engines had a pretty agressive ring pack for oil consumption and oil control. Especially with the second ring being a scraper design ring. Common on a lot of European engines that operate at higher RPM that need the agressive bore finish for lubing the top rings but need the scraper second ring to help with the oil control. There is a fair amount of friction in that ring package, though, so the changes were made to reduce friction, and to move the rings closer to the top of the piston to reduce HC emissions. The rings were made thinner at the same time to improve flexibiilty and reduce the tendency to flutter at high engine speeds.

Have you used the "whip" schedule on the 98 to see if it helps free the rings and reduce consumption?

ljklaiber
01-29-04, 09:13 AM
Bbob provided excellent fundamentals of piston and ring tech. TY!

Ring styles and location vary by application, but all function under high pressure, Racing rings may be of the Dykes type or more recently, a thin ring with gas ports put on the piston itself. Proper warm up and proper operating temperature are important because the piston grows and the gaps of the rings narrow with heat. Pistons are tapered and camground by design to accomadate heat expansion. The temp at the top ringland and crown are far higher than those at the oil ring stack, which consists of two thin rails and an expander which provides tension .
As for crankcase windage, If the counterweights contact the volume of oil, the froth is mostly air and hot gases that spike oil temp in a hurry. Better to be a half qt less than halfqt overfilled.

Racing Circle track over the years, we made most all the mistakes, and the help from engineers like Bbob was very valuable. Good thread! :bouncy:

BeelzeBob
01-29-04, 01:18 PM
jklaiber....thanks for the confirmation.

I should add to the post to confirm the impact the top rings have on oil consumption that, at one point in time, a small group of production Northstar engines were erroneously assembled (this was back in 1995 or so...) with the second ring UPSIDE-DOWNWARDS. The second ring, being a very aggressive stepped, scraper ring on that piston design, is used a lot in the oil control. Just ONE second ring turned upside downwards cause that cylinder to blow copious blue smoke, oil foul the plug and result in about 100 miles/quart oil consumption. Just illustrates that a considerable amount of oil (purposely) gets by the oil control rings, that the upper rings do contribute significantly to oil control and consumption and that there is enough oil past the oil rails to creat a 100mile per quart oil consumtion issue with the second ring inverted.

BTW....there were only a few of these engines and they were all caught in-house and never delivered to a customer as they were pretty obvious when started for the first time. A perfect "self policing" error. But it was good reminder of what the various rings function as.

The other item concerns the oil fill level and the 7 quarts in the sump of a Northstar. The sump was originally designed and baffled around a projected 5 quart fill. This was the ultimate goal of the design, but, once starvation testing and high G lateral track work started it was obvious that, to avoid uncovering the pickup, the sump needed 7 quarts in it. There was a LOT of development done to reduce this to no avail. If you are going to do high G lateral cornering then make sure the dipstick is on the "full" mark hot. Otherwise, for normal operation, 5 quarts is actually fine, functionally. On the straight and level the system will actually perform fine with down to about 3 quarts in the sump.

Want to know the quickest way to gain 5 HP in a Northstar engine....????.....drain 2 quarts of oil out of the sump and run it on a dyno at 5 quarts. We have run at 6000 on the dyno with as little as 3 quarts in the system and it will not starve...and it keeps making more and more power because the lower oil level leaves more room for ventilation or windage between the bulkheads and the oil level...and less oil is picked up by the crank and windage action causing frictional losses.

Actaully a lot of drag racers pick up on this with all types of engines running very low oil levels at the drag strip to reduce windage. If the pickup is properly located to not starve on accel then the low oil levels are free HP...

JohnnyLfromCT
01-29-04, 01:26 PM
Hey,

What's the story with checking the oil dipstick when the motor is hot?

I thought you are supposed to let the motor cool a bit, & the oil to drain back down into the pan to get an accurate reading? :confused:

BeelzeBob
01-29-04, 01:42 PM
Hey,

What's the story with checking the oil dipstick when the motor is hot?

I thought you are supposed to let the motor cool a bit, & the oil to drain back down into the pan to get an accurate reading? :confused:

This question was addressed in a similar post in the "eldorado/seville" section I think.... Look for the post entitled "goofy oil dipstick" or something like that. The jist of the answer is as follows. I just cut and pasted so it reads a little funny out of context but you can get the drift....

The dipstick was carefully engineered to be read when the oil was HOT. The oil does expand slightly when hot causing a possible overfill if the level is brought up to the full mark cold. The oil drains down very quickly in the engine. The idea that it takes hours to drain down is not accurate. Consider this....the Northstar oil pumps about 12 gallons per minute at 6000 RPM. With 7 quarts in the sump that means that the oil makes about 6 trips "around" the engine every minute. It must drain down pretty darned quick or the pan would be empty and the oil pressure would drop in about 6 seconds at 6000 RPM. By the time you have opened the door and opened the hood 99% of the oil is in the pan. Check it hot. That is the way it is designed.

Putting the 7.5 quarts in with a dry filter is absolutely correct. If you do find that the dipstick reading is a bit below the full mark when the oil is hot then mark the spot with a filed notch for reference. There is a little variability between dipsticks, the tube that they go into and the seating of the tube in the block. Due to these engine-to-engine differences yours might be off a little but probably not much when you check it like this.

By now you've noticed that the Northstar is not a "conventional" Cadillac engine. At 300 HP it makes over 1 HP per cubic inch...something no hot rodder could do back in 1955 much less with a production car!! To handle the 6500 RPM upshifts and high speed operation and slosh during hard cornering the lube system had to be carefully developed. That is one reason that the sump holds 7 quarts instead of the more conventional 5 quarts.



Bottom line is that the 7 quart fill is very close to being what the maximum the sump can function with. It does not like to be overfilled at all. Since most people check the oil when hot (gas station, etc..) the decision to base the dipstick calibration on hot oil was made. The oil drains down very very quickly as described and illustrated so that is not an issue with accuracy. Check it yourself. Run the engine on the freeway so the oil is very hot. Stop and check it as quickly as you can. Let it sit for several hours and keep checking it. I think that you will find that the Northstar has adequate drainbacks to have all the oil back in the pan in moments. Since the valley of the engine is dry there is no oil to drain back from there. The heads have several large, dedicated drainback passages that go straight to the pan and exit below oil level so the heads will drain rapidly and will not cause aeration or windage lossed by landing on the crank. Those large bosses or webs on the side of the block are actually the oil drainback passages.

ljklaiber
01-29-04, 03:47 PM
! We have run at 6000 on the dyno with as little as 3 quarts in the system and it will not starve...and it keeps making more and more power because the lower oil level leaves more room for ventilation or windage between the bulkheads and the oil level...and less oil is picked up by the crank and windage action causing frictional losses.)



This brings us to one of the main advantages of the Dry Sump oiling system.
The Two CTS-V's that run Sebring, may likely have Dry Sump oiling. I am sure the others here are looking forward to their getting a good finish in the race.

Also, keep us posted on the GXP. The only way I get my Seville back is a new car for my wife, and she likes the looks and engine in the new Pontiac GXP.

BeelzeBob
01-29-04, 06:31 PM
[QUOTE=ljklaiber

This brings us to one of the main advantages of the Dry Sump oiling system.
The Two CTS-V's that run Sebring, may likely have Dry Sump oiling. I am sure the others here are looking forward to their getting a good finish in the race.

Also, keep us posted on the GXP. The only way I get my Seville back is a new car for my wife, and she likes the looks and engine in the new Pontiac GXP.[/QUOTE]


Yea, the dry sump systems make some power due to the windage reduction and allow the crankcase to be evacutated to below atmospheric so that there is even "less dense" stuff to push around in there. Plus any problems with ground clearance and cornering starvation are eliminated. Nice to have 5 gallons of oil on board, too, for cooling and de-aeration.

I would suspect that the CTS-VR's might have dry sumps if the rules will allow. Heck, they may even show up on production cars one day....LOL

Did you see the post on the GXP in the Cadillac Lounge section.

El Dobro
02-01-04, 01:17 AM
Hey bbob,
I bought the 98 with 59000 on the clock. I don't know how the previous owner drove it,but it gets exercise with my foot now and the oil consumption is going down little by little.

Next time I get a chace, I'm going to post a couple of questions on drivetrain problems.