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Northstar Engines and System Technical Discussion Discussion, Northstar Oil Usage in Cadillac Engine Technical Discussion; Hey, I am looking for some information on the oil usage of the northstar engine. I am looking at a ...
  1. #1
    Buddy94 is offline Cadillac Owners Member
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    Northstar Oil Usage

    Hey,
    I am looking for some information on the oil usage of the northstar engine. I am looking at a 2000 STS. If I purchase it, it will be my second Caddy. I have heard that the northstar engine requires a quart of oil every 1400 miles. For the past six years, I have driven my 94 Caddy with the 4.9L from Arizona to Florida with no loss of oil. Does anyone out there have a northstar engine? If so, can you share some information on this topic?

    Buddy94

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    Anthony Cipriano is offline Cadillac Owners Fanatic
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    Re: Northstar Oil Usage

    Quote Originally Posted by Buddy94
    Hey,
    I am looking for some information on the oil usage of the northstar engine. I am looking at a 2000 STS. If I purchase it, it will be my second Caddy. I have heard that the northstar engine requires a quart of oil every 1400 miles. For the past six years, I have driven my 94 Caddy with the 4.9L from Arizona to Florida with no loss of oil. Does anyone out there have a northstar engine? If so, can you share some information on this topic?

    Buddy94
    There has been a lot discussed on Northstar oil consumption. Search in the archives for more info. It's not unusual for a Northstar to use more oil than some other engines. It's a high performance engine and has to allow a little more oil to the top rings for lubrication as as well as down the 32 valve guides.

    Design intent for oil consumption would put the engine at about 4000 miles per quart consumption but due to the variables in production parameters there are engines that will use 1 quart per 1000-1500 miles - perfectly normal and acceptable - but more oil consumption than "intended". Nothing will be wrong with the engine but the continuous oil adds are aggravating. If this is the case then understand that the engine is probably going to run a long, long time like that as the cylinder walls, rings, valve guides, etcetera like all that oil that you are putting in and the continuous oil adds fortify the used oil in the sump and replenish the additive package in the oil that is slowly depleted under normal usage.

    Comparing the 4.9 to the Northstar is an apples to oranges deal. The 4.9 is an excellent engine for it's purpose but does not offer nearly the performance, durability, fuel economy and emission control capability of the Northstar. The Northstar is a high output engine and likes to be "used".

    The best way to minimize oil consumption in a Northstar is to keep the sump filled slightly low (many are continuously overfilled) by only checking the oil level when hot and only filling the sump with 7 quarts of oil (7.5 with a dry filter at a change.) A typical 8 quart fill at a change is "required" to put the oil level on the full mark when cold but is actually overfilling the crankcase promoting oil consumption.

    Use conventional mineral oil (synthetic is not required at all) as it tends to provide better oil consumption.

    And last but not least, air the engine out frequently. It likes to be used and red-line upshifts at wide-open throttle help promote clean combustion chambers, exercise the piston rings to keep them free of carbon buildup and keep them mobile and to ensure the engine is broken in and maximum sealing is obtained. The Northstar does not like to be babied around. It likes to be run hard frequently with a WOT blast in merging or whatever. Even engines reported to use 1 quart per 1500 miles tend to improve to 2500 miles per quart or better when subjected to a regular schedule of use and "abuse".

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    Anthony Cipriano is offline Cadillac Owners Fanatic
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    Re: Northstar Oil Usage

    Quote Originally Posted by Buddy94
    Hey,
    I am looking for some information on the oil usage of the northstar engine. I am looking at a 2000 STS. If I purchase it, it will be my second Caddy. I have heard that the northstar engine requires a quart of oil every 1400 miles. For the past six years, I have driven my 94 Caddy with the 4.9L from Arizona to Florida with no loss of oil. Does anyone out there have a northstar engine? If so, can you share some information on this topic?

    Buddy94
    Buddy. This is a copy/paste of a message posted some time ago. I hope it helps...

    The subject of oil consumption really does not have a "final" answer. The fact is that there is some variability in oil consumption in all production engines. Regardless of who makes them on which continent. All the manufacturers recognize this and virtually all of them will call oil consumption as great as 1 quart in 1000 miles "normal", "acceptable", "allowable", "within production tolerances" etcetera. This doesn't mean that all engines will get 1000 miles per quart (MPQ) or that the engine was designed to get 1000 MPQ. It just recognizes the fact that there are going to be some engines that get 1000 MPQ that will be perfectly fine upon disassembly and will have nothing "wrong" with them.

    The variables that usually enter into oil consumption are primarily associated with the piston/ring/cylinder bore. The number of valves or type of valve actuation has little to do with it.

    The single biggest variable and the one that haas been discussed at great length on this forum is the cylinder bore finish or the cylinder honing pattern. The higher perfromance the engine is the more attention must be paid to the honing pattern and retention of oil on the cylinder walls to lubricate the piston and rings at full load, high RPM operation. The Northstar engine uses a very agressive cylinder bore finish that tends to retain a lot of oil to protect the piston and rings. When the blocks are honed at the factory there is a tolerance in the bore finish due to the fact that the honing stones will wear and need replacement. A brand new stone gives a slightly more agressive pattern than a "used" stone. So a block honed with new stones will have a more aggressive finish and most likely will use more oil.

    Another variable is bore roundness. Like it or not, the bores tend to "move" slightly as the engine heats up and cools down and bolt tensions relax over time. All this contributes to slight bore out of roundness that is not bad or good - just different.

    Carbon buildup in the rings and reing sealing are also variables that come into play with breakin, operating schedule, type of oil used, etcetera.

    The one thing that I can attest to is that many, many customer oil consumption complaint engines have been torn down with absolutely nothing wrong found. The engines are often reassembled and put into test cars and driven by the engineers and more often than not the high oil consumption does not repeat itself. The single most common cause seems to be break-in or lack there of. Many, many oil consuming Northstar engines are "fixed" by some full throttle operation. We often joke about "driving it like you stole it" but it really is no joke. The Northstar engine was designed as a high performance engine to be run hard and fast. Those that are run hard typically exhibit excellent ring seal, little carbon build up and good oil economy. We have seen engines with tens of thousands of miles on them that the rings have not sealed or mated to the sides of the ring grooves because the operating schdule was so light duty. The moral here is to flog it often.

    In any case, the nice thing about the engines with the more aggressive honing pattern is that the pistons, rings and bores will last forever. It is very common to tear down a 200,000 mile Northstar engine and still see the original honing pattern in the cylinders. There is never any sign of cyilnder wall wear and the idea of a wear "ridge" at the top of the cyilnder bore is something that is laughable on a Northstar.

    The other nice thing about a little oil consumption is that it adds tremendous safety factor to the oil change interval. Nothing could be better for the engine than an occasional quart of fresh oil. You can take the worst oil on the market and add a fresh quart every 1000 miles and over the life of the engine the wear will be better than an engine run on the best oil with no adds between changes.

    While no one in the engineering commumnity wants high oil consuption the fact is that there is some variability in the oil consumption of an engine manufacturered at the rate of 1200 per day. The specs of what is "normal" simply reflects this - it does not imply that all engines whould get this or that somthing is wrong with and engine that gets more or less oil consumption.

    There have been a lot of engineering changes over the years on the Northstar aimed at reducing the overall oil consumption and reducing the variability in the oil consumption of different engines. Many changes have been made to the honeing process to make it moe consistent. Changes to the piston and ring groove treatment have been made to make it more resistent to wear, poundout and microwelding at low oil retention rates. Regardless, there is still some variability.

    One other thing that affects oil consuption, or the customers perception of oil consumption, is the move toward longer and longer change intervals. With the allowable change interval reaching as high as 12,500 miles on a 2003 Northstar if the oil life monitor is followed this could mean the addition of 3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oil every 2000 or 3000 miles, despite the oil life monitor recommendations, then they would not have to add any oil between changes. The oil consumption is the same - the amount added between changes is all that's different. Yet, many customers do not make the distinction. Field surveyrs repeatedly show that "acceptable" oil consumption means "not having to add between changes" - whatever MPQ that is.

    The issue of oil consumption is very emotional, too, as many people perceive higher oil consumption as 'poor quality" or an indication that something's wrong. Blue smoke, fouling plugs, noise - those are signs that something's wrong. Using 1 quart in 1000 miles might be perfectly normal for an engine that has the high limit "rough" hone finish and is perfectly in spec. Yet it will be perceived differently.

    The Northstar engine in particular was designed to be a high performance engine and to perform well at high speeds and high loads. The engines are tested at loads and speeds for time periods few customers will ever be able to duplicate. It's unfortunate that the engineering that goes into making the engine capable of such running sometimes contributes to more oil consumption - especially as the production machining tolerances are taken into account.

    The items mentioned about overfilling also apply. Make sure that the system is not overfilled as any excess oil will be pushed out the PCV. The best bet is to always check the oil hot and keep it midway between the add and full mark. Don't always top off and don't top off cold to the full mark as that will overfill the sump.

    I hope this helps rather than adding more fuel to the fire. No pun intended.

    Incidentally, there's a lot in our archives. Check using "oil consumption" and read on. Always keep in mind that for every "oil burner" you read about on the internet there are 10,000 or more driving around perfectly fine that the people aren't posting about. You're always going to read about the horror stories on the internet. How many people search Google for a Cadillac forum just to post about how they haven't had a particular issue?

    If you had a BMW then you must enjoy the www.my750.com site. Typical "hate site" that pops up to promote so called "epidemic" problems with a particular product.

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    Buddy94 is offline Cadillac Owners Member
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    Re: Northstar Oil Usage

    Thanks for the info. Just returned from Don Mackey Cadillac in Tucson. I spoke with a gentleman who goes by the name of Chuck. He stated that a N* should get about 3000 miles before adding any oil. He went on to say that his customers get their every service done 3000 miles without adding oil between services.

    I went to Lawley Cadillac in Sierra Vista and the person there confirmed what this site was saying (1000-1400 MPQ). It was explained that there was nothing wrong with the engine; it was designed to work that way. They took the time to explain a lot more to me. It was not a sales pitch, considering what I received in Tucson. I will, however, keep my 94 Caddy with the 4.9L for now. Thanks for the help and all the info I received.

    Buddy94

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    c_a_s_2 is offline Cadillac Owners Member
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    Re: Northstar Oil Usage

    What is your opinion on use of SLICK50 in my Northstar? I bought it, but have not added it, yet. Waiting for oil change time. My car is 98 eldo, 40K, no drips, and very low oil consumption, right now. .........I just want this car to Last and Last and Last. cs

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    Anthony Cipriano is offline Cadillac Owners Fanatic
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    Re: Northstar Oil Usage

    Quote Originally Posted by c_a_s_2
    What is your opinion on use of SLICK50 in my Northstar? I bought it, but have not added it, yet. Waiting for oil change time. My car is 98 eldo, 40K, no drips, and very low oil consumption, right now. .........I just want this car to Last and Last and Last. cs

    Please don't waste your money...

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    std1 is offline Cadillac Owners Member
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    Question Re: Northstar Oil Usage

    I have had 3 Northstar equipped Cadillacs and know about 5 other people who have had them as well. Like clockwork, the heavy oil consumption seems to begin after 40,000 miles. I know an engineer who obtained a Northstar engine from a junkyard and cut it into cross sections. (He said Northstars are widely available due to their not being conducive to rebuilds) This engineer noticed that the cams in the Northstar seem to meet the valve stems at a somewhat acute angle which suggests a side movement pressure to the valves in addition to the expected up and down movement. He stated the valve guides in the engine he examined were worn. The question here is has anyone ever factually demonstrated that valve guide wear is not a factor in the Northstar's prodigious oil consumption?

    Prior to the 3 Northstar equipped STS's I have had, I had a '93 with the 4.9 litre engine. I sold to my brother who still has it with an excess of 240,000 miles and it still does not use oil. The 4.9 litre engine was far more enjoyable to drive around town. Its 2 valve per cylinder design provides nice low end torque for everyday driving which is really what most people want most of the time. Load up a Northstar car with people and A/C and the idea of having to thrash and mash the pedal to get it to respond slight speed changes is draining on both my energy as well as the gas tank. The 4.9 only needed only a slight bit more pressure on the accelerator to respond very well. Also, how much $3.00 per gallon gas has to be wasted in order to get the rings to re-seal?

    I do not know if I will ever understand the reasoning that went into putting the Northstar into a street car. It is only fun to drive when the pedal is to the metal but how often can one do that. A friend of mine was just visiting with his 740iL. The engine sounds as smooth as a sewing machine and the car does not shake at all. In contrast, the overly complex Northstar design creates a disconcerting sound. Something like a "clanking and clattering cacophony of cams and cogs".

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    Re: Northstar Oil Usage

    My Northstar seem to take very little pedal to get it moving and gives back excellent fuel milage. Have you read the Technical Archives at the top left of this page regarding oil consumption?

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    STS-in-Nottingham is offline Cadillac Owners Fanatic
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    Re: Northstar Oil Usage

    Quote Originally Posted by std1 View Post
    In contrast, the overly complex Northstar design creates a disconcerting sound. Something like a "clanking and clattering cacophony of cams and cogs".

    I've owned two STS's and neither of them made any clanking or clattering noises.
    Both drive beautifully at normal speeds too, silky smooth and whisper quiet.
    Connan1 likes this.

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    Re: Northstar Oil Usage

    If the valve guides were the culprit for oil consumption, wouldn't this result in a smoky exhaust at startup as the oil which seeped down the stems would be burnt in the first 15 seconds of running? Without a noticeable smoky exhaust, I tend to believe the theory that the oil consumption is due to the agressive crosshatching of the cylinder sleeves.

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    Re: Northstar Oil Usage

    Last year I drove my 96DeVille up Cadillac Mountain is AcadiaNationalPark up Maine. Catch the sunrise there [I didn't] and you are the first in the Continental US to see it.

    On the way down I dropped into 2nd and allowed the engine to hold the car back to save the brakes and enjoy the wonderful view.

    Well once at the bottom I kicked it up into OD and resumed a 40MPH pace. Well I was quite surprised [though not as surprised as the fellow behind me] to see huge white billowing clouds coming out from behind. Whoa!!!

    I qiuckly pulled over and poped the hood and looked around. Nothing seemed out of the ordinary, oil was in the hatches, temp was no problem???

    I resumed driving and all cleared up. I did post here, but NO ONE bit. My suggestion was valve guides AND infact this might be part of the oil comsumption mystery. There's 32 of 'em for godsakes.

    How about a little feed back on the valve guide issue. K_C

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    std1 is offline Cadillac Owners Member
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    Question Re: Northstar Oil Usage

    I spoke to a old race engine builder I know and he suggested finding out what type of piston rings are used on the Northstar. Here is his response: The nature of bore finish has long been a topic of discussion amongst engine builders of all persuasions. For decades, engines used iron or hard chromed steel rings. The latter, in particular, demanded a long break-in period but exhibited excellent life (locomotive and marine Diesel engines use chrome rings, for example). In order to encourage the best possible seal with these ring types during the break-in period, relatively agressive cylinder wall finishes are recommended by engine manufacturers.

    The development of barrel-faced molybdenum disulfide coated piston rings for automotive use changed all that (the first widespread usage of this ring type, I believe, was in the Chevrolet 396 big blocks of the mid-1960's). In fact, the developer of the BF moly ring advised that engine builders hone the cylinder walls to a much smoother finish than previously recommended, as a lengthy break-in period was no longer required and the ring would seal better. My racing experience over the years more than confirmed the validity of that advice. In "How to prepare Chevy V-8s for racing" book published by GM in the early 1970's, it was recommended that the cylinder preparation process culminate in the use of polishing pads (similar to crocus cloth in abrasivity) to produce the smoothest possible core finish. They explicitly warned against using a bore finish that was suitable for use with iron or chrome rings, as it would cause rapid wear to moly ring, resulting in high oil consumption and early ring failure.

    The whole purpose of the moly coating is to reduce the amount of sliding contact between the metal part of the ring and the cylinder wall. In fact, the ring design was such that under low cylinder pressure conditions (i.e., during the intake stroke) the loading on the cylinder wall was minimized and most of the sliding contact was between the moly coating and the wall. The application of pressure to the compression side of the ring would cause it to twist slightly, thus producing a tighter seal. The rings were marked so the installer could determine which side was up, as accidentally inverting them would result in a huge amount of blow-by. The use of a smooth bore finish promotes this property, resulting in better sealing at high engine speeds, at least up until the point of ring flutter is reached which would not be a problem with the NS as it does not develop a high enough piston speed at redline.

    General Motors developed the moly ring and wrote the book on how to use it. IF they are using a moly ring in the NS engine with the coarse bore finish (as discussed by other members in this forum) then it seems that they have either ignored their own research (which does not make sense as many a racing engine has survived with smooth bore finish and moly rings let alone engines designed for street cars) or they have an unaddressed production problem.

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    Re: Northstar Oil Usage

    My Northstars has always used oil. I add a quart at about the 50-60% of life. I've had two engines. Not a real problem but I do check it now ahead of the "low oil" message.

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    Re: Northstar Oil Usage

    Quote Originally Posted by std1 View Post
    I spoke to a old race engine builder I know and he suggested finding out what type of piston rings are used on the Northstar. Here is his response: The nature of bore finish has long been a topic of discussion amongst engine builders of all persuasions. For decades, engines used iron or hard chromed steel rings. The latter, in particular, demanded a long break-in period but exhibited excellent life (locomotive and marine Diesel engines use chrome rings, for example). In order to encourage the best possible seal with these ring types during the break-in period, relatively agressive cylinder wall finishes are recommended by engine manufacturers.

    The development of barrel-faced molybdenum disulfide coated piston rings for automotive use changed all that (the first widespread usage of this ring type, I believe, was in the Chevrolet 396 big blocks of the mid-1960's). In fact, the developer of the BF moly ring advised that engine builders hone the cylinder walls to a much smoother finish than previously recommended, as a lengthy break-in period was no longer required and the ring would seal better. My racing experience over the years more than confirmed the validity of that advice. In "How to prepare Chevy V-8s for racing" book published by GM in the early 1970's, it was recommended that the cylinder preparation process culminate in the use of polishing pads (similar to crocus cloth in abrasivity) to produce the smoothest possible core finish. They explicitly warned against using a bore finish that was suitable for use with iron or chrome rings, as it would cause rapid wear to moly ring, resulting in high oil consumption and early ring failure.

    The whole purpose of the moly coating is to reduce the amount of sliding contact between the metal part of the ring and the cylinder wall. In fact, the ring design was such that under low cylinder pressure conditions (i.e., during the intake stroke) the loading on the cylinder wall was minimized and most of the sliding contact was between the moly coating and the wall. The application of pressure to the compression side of the ring would cause it to twist slightly, thus producing a tighter seal. The rings were marked so the installer could determine which side was up, as accidentally inverting them would result in a huge amount of blow-by. The use of a smooth bore finish promotes this property, resulting in better sealing at high engine speeds, at least up until the point of ring flutter is reached which would not be a problem with the NS as it does not develop a high enough piston speed at redline.

    General Motors developed the moly ring and wrote the book on how to use it. IF they are using a moly ring in the NS engine with the coarse bore finish (as discussed by other members in this forum) then it seems that they have either ignored their own research (which does not make sense as many a racing engine has survived with smooth bore finish and moly rings let alone engines designed for street cars) or they have an unaddressed production problem.
    My understanding is that the north* has a bore finishing process that starts with a coarse honing pattern to hold oil followed by a fine honing process that smooths the peaks into plateaues. The result is the best of both worlds; grooves to hold lubrication and a smooth surface for ring longevity.

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    Re: Northstar Oil Usage

    Quote Originally Posted by Buddy94 View Post
    Thanks for the info. Just returned from Don Mackey Cadillac in Tucson. I spoke with a gentleman who goes by the name of Chuck. He stated that a N* should get about 3000 miles before adding any oil. He went on to say that his customers get their every service done 3000 miles without adding oil between services.


    Buddy94

    I have a 93 an old one and it just turned 100k I changed the oil when I purchased the car and have put 3k miles on it.During that time I have had to add just 1/2 a qt. I just checked it today before a long drive to the airport and it is still full.I dont see this thing burning realy hardly much oil at all.Maybee I just got lucky. My self personaly a V8 with 100k
    and very little oil consumption says a lot about how well this engine was builtN*

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