M42 oil consumption

[JHZR2]

My 91 318i is at less than 500 miles per qt of oil. 173k miles young, it runs like a top, same as it ever has, no signs of where the oil is going (per previous threads). At this level shouldn't I see some smoke or at least some oily dampness on the tailpipe?

I wouldn't be afraid to drive this car cross country tomorrow. I would just go through a lot of oil. There is never a drop of oil when I park the car, so I know I'm not linking even if it's coming out only under high engine speed. Unless it drips out and land so perfectly that it leaves the underside of the car absolutely clean.

What gives??

What's the best test to verify that it is actually burning? All floor plugs look the same and are clean.

 

[spasm3]

I think it takes a lot to show up if you have good compression. Low compression and it does not burn as clean. My sons sc1 saturn will go through a quart in about 700 miles yet you cannot see any blue smoke or smell it. Saturns have a piston design that does not drain oil back from the ringlands and low tension oil rings. They burn oil despite having really good compression. Perhaps you have good compression yet bad valve seals.

 

[Quattro Pete]

Originally Posted By: JHZR2
My 91 318ibis at less than 500 miles per at of oil.

Typing fail.

 

[JHZR2]

I've got something. The car has some rust that's growing, so though it's debt free and I absolutely love it, we've decided it's the one to go when we get a van. Still while I'm using it at 300+ miles a week, I want to keep track of things and not ruin it. My hope is it goes to someone at a trade school or something like that to mend the rust and work the engine.

 

[spasm3]

Originally Posted By: Quattro Pete
Originally Posted By: JHZR2
My 91 318ibis at less than 500 miles per at of oil.

Typing fail.

Probably sending this from his phone.

 

[JHZR2]

Originally Posted By: spasm3
Originally Posted By: Quattro Pete
Originally Posted By: JHZR2
My 91 318ibis at less than 500 miles per at of oil.

Typing fail.

Probably sending this from his phone.



Yup. Voice recognition has its flaws, as do fat fingers

 

[spasm3]

Originally Posted By: JHZR2
I've got something. The car has some rust that's growing, so though it's debt free and I absolutely love it, we've decided it's the one to go when we get a van. Still while I'm using it at 300+ miles a week, I want to keep track of things and not ruin it. My hope is it goes to someone at a trade school or something like that to mend the rust and work the engine.


sounds like a good car for a high school kid. It will teach him to check the oil.

 

[Doog]

Ever pulled a valve cover?

 

[Kool1]

My CRV drinks Castol Syntec oil (1.5 quarts in 5,000 miles); however, it does not drink Mobil1 EP. Both oils are the same weight. I have no idea why this happens to me but it does.

 

[michaelluscher]

Sounds like time to pull its head and send it off for a refurb.

Have you done a wet/dry compression test and a cylinder leak down test? Perhaps some UV dye in the oil, really start looking around for leaks.

 

[JHZR2]

Originally Posted By: Doog
Ever pulled a valve cover?

 

[JHZR2]

Originally Posted By: michaelluscher
Sounds like time to pull its head and send it off for a refurb.

Have you done a wet/dry compression test and a cylinder leak down test? Perhaps some UV dye in the oil, really start looking around for leaks.


I did a compression test a while ago, all came back good.

I wont be pulling the head, it runs great and we have to get a minivan at some point before too long...

 

[Brons2]

Well, hard to argue with that as far as cleanliness goes.

Have you tried 20w50 for the consumption?

 

[JHZR2]

Originally Posted By: Brons2
Well, hard to argue with that as far as cleanliness goes.

Have you tried 20w50 for the consumption?

Yes.

I typically ran syn, but it was just burning dollar bills too fast. Used 20w-50 for no real improvement before it got too cold.

So the question really becomes if Im better off running a lighter oil that will likely burn easier, or a heavier oil that is less volatile, that is still consumed, since it may contaminate more things...

 

[spasm3]

I might not run an hdeo unless you just have to. The high zinc and detergents might get to the cat over time.

 

[JHZR2]

That's why ive moved to conventional oils.

 

[901Memphis]

Have you tried liqui moly motor oil saver yet?

 

[toneydoc]

Go to petroleum quality institute site and look for low NOACK numbers. Don't know if that will help with consumption.

 

[Astro14]

At 173,000 I wouldn't be worried about the cat. Run whatever you like.

 

[Challenger71]

leak-down test. It's likely one or more of your rings (oil scraper or compression)