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Discussion Starter #1
This discussion will go over the issue of Northstar engines mysteriously losing oil. Most people aren't sure whether the engine is actually leaking or burning the oil. Many people don't find leaks in their driveway. So what's the problem? Has it been fixed in later models? Are there any particular years that are better or worse?
 

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White Diamond 2001 STS
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Using oil...

Usually, the Northstar is just using oil, rather than leaking it out. The Northstar has a very aggressive cylinder hatch pattern, to promote sufficient oiling at high engine speeds (6000 rpm). Unlike many engines, this thing was designed for sustained high rpm use and will run at 6000 rpm all day. The aggressive hatch pattern tends to retain the oil longer than a slicker cylinder wall will.

Naturally, this oil retention keeps the oil up in the piston rings, which is good for lubrication, but it also means that it'll use more than "normal". GM has stated that 1 qt. for 1000 miles is satisfactory. We're used to a "good engine" not using any oil at all, but those engines also need rebuilds after 100,000 miles due to worn out cylinders (less lubrication means more wear). The Northstar is good for many many miles and the oil usage is a small price to pay for this reliability.

Having said that, there's also a tendency for the oil to find its way out of any small and minor imperfection in the block seal area. Not every engine does it. Mine never leaks onto the ground, but it is usually damp down there, meaning that a very minute amount of oil does seep out. It's no big deal and certainly nothing to be concerned about. Rarely does the case half leak drop more than a drop or two every night. If you have a oil leak that's producing a puddle on the ground, it's probably not the case half leak, despite what your Cadillac dealer will probably diagnose it as.
 

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Discussion Starter #3
Thank you for this information! This is good news to me. I have to tell some of my friends to come see this thread. I know Cadillac backed themselves up by allowing more oil that usual anyway. What you said makes great sense, though.. I think I'd rather have it work this way and feel confident that my engine will last longer.
 

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1995 SLS 200K miles
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I'll try to pass on the tech of why crosshatch angle , depth and stone selection, is purely a way of seating the ringface.

I have a well used 95 sls with 137k miles. It uses No oil. It drips 2 or 3 drops when run long and hard. I changd at 3k miles including Wix filter i added 6.5 Qt.. (just into the stick area that says ADD!

I have dyno tested synthetics on a Superflo 901, and we still race mineral oil ............changed weekly.
Synth is ok, but definately NOT worth the cost.

Alloy engines appreciate a patient and careful warmup. Aluminum expands over twice as much as iron.

NS is a beauty!

Buy th correct fuel for your yearmodel. I use 93 AMOCO in my 95.

Happy New Year!
ljk
 

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Another thanks for Jason's info. I have never heard this "simple" (meaning as a compliment!) explination before.

Paul G.
 

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White Diamond 2001 STS
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Another thing to mention is that oil usage is usually directly related to how hard you run the car. The more time you spend at redline, the more oil you'll normally burn.

Mine's pretty consistent like that. If I drive it easy, it uses hardly any oil at all (ALL engines use some oil). If I drive it really hard during a two or three week period, it'll use a quart or two.
 

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Just wondering, Jason....are you a teacher at Tech? Your concise comments on engineering-type topics lead me to think as such.
 

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No...coulda been...sort of. :)

I just graduated with a Technology Education degree, which prepares me to teach tech. ed. in secondary schools. Courses like the (now somewhat rare) woodshop and metalshop classes to the more common technology-based courses (like construction technology, transportation technology, etc.). I found that, at least at this point in my life, I don't enjoy teaching enough to warrant me being in a classroom. I don't enjoy the art of teaching enough to make a difference for the kids (so I'm staying out, for now).

I'm the project manager at a local engineering firm for their GIS department (Geographic Information Systems). Geography and maps are another one of my hobbies (besides cars/engines). Although my tech. ed. curriculum gave me lots of auto/engineering experience, I've learned a lot of what I know from personal experiences and participating on boards such as these.

Thanks for the compliment, though. I really do enjoy mechanical engineering and internal combustion engines. Just didn't have the discipline in school to do an engineering degree. ;)
 

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I believe it is always a good thing to have the younger folks involved on any dialogue. Us old guys have had our day, and we need to pass on what we can and wish all the young our best.

My best to all of you. Auto racing is the finest sport in the whole damn world.

Carry On!
 

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I have a 97 deville concours that's hitting 95k mi currently on odo
My engine was replaced between 55k~65k because i complained about oil consumption constantly and all their solutions didn't work. Starting last summer my car started to overheat periodically. Once it overheats it will get all the way into red when i'm stopped and temp decreases once i'm moving. This has happened several times since dealer didn't have any answers other then telling me to bring the car back when it's overheating!?! (Work --50mi-- home --15~20mi-- dealer = 65~70mi while overheating).
Currently my car is using more than 3quarts of oil in 800mi. They are currently working on it but i have a feeling that it's not going to be fixed. I think the dealer messed up my ac system too but that's another problem for another day
 

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Can you replicate the over-heating problem when you're at the dealer? 3 quarts of oil in 800 miles is a lot. Is your car under warranty? This was a $3000.00 job when it happened to me but the car was under warranty so I only paid a small deductable...
 

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Anthony Cipriano said:
Can you replicate the over-heating problem when you're at the dealer? 3 quarts of oil in 800 miles is a lot. Is your car under warranty? This was a $3000.00 job when it happened to me but the car was under warranty so I only paid a small deductable...
what your telling me is to drive 70mi while the car is overheating. Of course not. I usually end up filling the car up with 3~4 gallons of water. I think when the car begins to overheat my coolant comes back through the small hose.

I can smell my coolants when i'm stopped at the traffic light (only when it's overheating). In fact i've seen the coolant pour down underneath the car when i waited for it to cool down in some parking lot.

edit- they did headgasket job for free because according to them, my engine is still under warranty. I suspect that gasket went bad because of all the heating issues. I guess technically car is still under warranty because i've been taking the car to them well before the gasket replacement.
 

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Any possibility of driving into the area of your dealing and kinda sticking around awhile to see if you can replicate the over-heating? That's what I should have said in the first place...
 

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well i didn't get to keep the car long enough to know whether it was going to overheat again since the gasket was replaced. I took the car back for bad spark plug(replaced by them), oil consumption, and ac leak.
so far i haven't got my car back and they want to charge me for the ac leak. There was no ac leak few months ago. There was no ac leak before they started transmission work and gasket exchange. It was after and i suspect that they did something to caused the ac to leak.
 

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This sounds like one of those situations I'd rather never be involved in. I guess the over-heating is just touch and go and you have to hope it's not going to happen again since the gasket was replaced.. And the a/c leak will be very hard to prove. Maybe if you sit and wait for the car to be finished, you could take the old part and see if it was damaged - wherever the leak was. I know waiting is probably not possible, though...
 

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GM has a supposed fix for some years of Northstar that involves cleaning the cylinders and piston rings. You squirt a special cleaner into the bores through the spark plug holes, then let the car sit for two hours for the cleaner to soak in between the rings, then vacuum the leftover cleaner out. Then you change the oil (without the filter), drive the car for 20 minutes, then change the oil *and* filter since the oil will now have the gunk from the cylinders. This is a job for a dealer, since the vacuum is a special tool designed just for this job.
 

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i've had that done twice but i don't see the difference in oil consumption before and after then again my car seems to be fubared by the dealer and it drinks more oil than normal north*
 

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I agree, My experience has been that... If you push'em hard they'll use some oil. If you don't they won't! If you break'em in right they'll use less oil over the life of the engine. I can build engines for guys that can be run hard from the get'go but It's more labor intensive....Katshot, you'll like that! It's a fancy way to say Mo' Money! I like to build them where you have to spend some time breaking them in ( at least 500 miles ) They seem to be a little more user friendly and not use quite as much oil in the long run. The trend as of late in the direction of engines that they claim need no break in period is not beneficial in the long run! It's just one more way to please an already too spoiled public!
 
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