Oil Consumption

[Guest drnittler]

I have a 61 Studebaker lark six cylinder. The engine was professionally rebuilt two years ago and has 3100 miles on it. I started with 30 w oil nad later went to Shell Rotella T 15w 40 becasue of the zink. When I did this for every 70 miles I would be down a quart of oil. I am not sure I am leaking or burning this oil.

Sometimes it runs on after shutting the car off.

Stuff I did:

The timing is ok and no overheating.

Checked for leaks, none were present on the engine, parts, ground, etc.

Tightened up all pan, etc bolts.

Checked the oil cap, PCV valve, etc All was ok.

The plugs are clean.

No smoke from the tail pipe

No fluids mixed with others, oil in antifreeze, etc.

Good compression numbers.

So what is left to look for? I am guessing the rings have not seated well.

Any thoughts or ideas are appreciated.

Thanks in advance.

[Owen_Dyneto]

I'm sure your problems are unrelated to the change in oil type. It should be really easy to determine if you're leaking it or burning it - a 70 miles per quart if you were burning it you'd have a blue could behind you for miles! Suggest you park the car with some clean paper or newsprint under the motor and leave it run for a hour so so. Any leak of that size should leave a huge puddle and should be very easy to track back.

[Guest]

Just to make sure there is no oil burning, what is the condition of your spark plugs? What is the compression on the engine? Do you get blue smoke on deceleration? Is that PCV valve and the tubing to it really oily?

Because your car was built before it was required to have exhaust emission controls, warmed up correct engine idle speed and timing is critical to prevent engine run-on after shutting down.

D.

[NTX5467]

Remember, the compression ring is separate from the "oil ring set". It's the oil ring set's job to scrape the excess oil from the cylinder wall on the down stroke of the piston. In other words, you can have good (even great) compression and the oil rings could not be scraping enough oil . . . er "doing their job".

Bearing clearance (too much) can flood the cylinder walls with oil, from "sling off" as the crank spins. If it's too much, even good oil rings can't get it all.

I concur that the change to Rotella T 15W-40 probably had very little to do with the oil consumption issue.

With all due respect, "professionally rebuilt" can mean anything from "a highly experienced machinist/engine builder" to "built in a business' shop" . . . so there can be lots of variation there rather than a generic, universal "good" situation. Even if it was done in a "good" shop, the actual assembly and such might have been handed-off to a less experienced employee . . . possibly.

If the oil is actually getting consumed, the spark plugs would hopefully "tell the tale". If the base hot idle speed AND mixture AND timing are correct, then the run-on could be due to combustion chamber deposits, of "some" origin. But with THAT much consumption, I'd expect them to be pretty much fouled and needing replacement.

In some respects, I suspect the zddp issue is somewhat overblown. IF your car has the original camshaft and valve lifters in their original positions, then there's probably enough zddp in normal motor oil to be fine in YOUR engine. It's been an observation that the real issues began when aftermarket/replacement camshaft manufacturers noticed the issue FIRST, plus other racing uses with very high engine speeds combined with replacement camshafts with very high valve lifts and very high valve spring pressures to support those things. Whereas you have a low rpm, low lift, low valve spring pressure stock motor, I suspect.

In order to determine if the Rotella is the issue, Edelbrock and others now have zddp additives you can add to newer motor oils. So you can go back to a straigt-weight 30 motor oil and then add the small bottle of zddp additive to it.

Worst case scenario, you might need to network with the local Studebaker "community" and see about a reputable and quality machine/repair shop. I suspect that the real issue might only reveal itself when the engine is removed and re-openned for inspection. Just my gut suspicion of what might end up happening.

Regards,

NTX5467

Edited May 25, 2012 by NTX5467 (see edit history)

[Guest drnittler]

Thanks one and all. I did the paper under the car deal and notning showed. How does one know if the rings seated?

[rhb1999]

Did the PCV have any suction when it was running?

[Owen_Dyneto]

As "helfen" suggested above, you might do a compression test to give some indication of the ring and valve conditions. Don't forget to insure both the choke and throttle valves are open when testing.

[rhb1999]

I have a 61 Studebaker lark six cylinder. The engine was professionally rebuilt two years ago and has 3100 miles on it. I started with 30 w oil nad later went to Shell Rotella T 15w 40 becasue of the zink. When I did this for every 70 miles I would be down a quart of oil. I am not sure I am leaking or burning this oil.

Sometimes it runs on after shutting the car off.

Stuff I did:

The timing is ok and no overheating.

Checked for leaks, none were present on the engine, parts, ground, etc.

Tightened up all pan, etc bolts.

Checked the oil cap, PCV valve, etc All was ok.

The plugs are clean.

No smoke from the tail pipe

No fluids mixed with others, oil in antifreeze, etc.

Good compression numbers.

So what is left to look for? I am guessing the rings have not seated well.

Any thoughts or ideas are appreciated.

Thanks in advance.[/quote/] Were the compression numbers even? How does the car run?,good? Does it have blow-by? Does a lot of smoke come out when you take the oil cap off? Maybe the piston rings were installed upside down or there mixed up so how. Or the cylinders were not honed.

[Guest drnittler]

Upon further checking I found a dripping under/from the base of the distributor. I had the car up on stands, newspapers under it, etc. The engine was running sort of fast. The drip was dripping pretty good. and hitting out past the left side of the engine on the papers. It would not seem like much, but would add up after 100 miles of driving. So I get a new gasket and repair it. I am hoping I will get lucky on this. More later.

Thanks again.

[Coley]

Exhaust valve guides can suck oil out of an engine and it won't show on plugs.

Once you have the drip fixed, that may help. If not try valve stem seals.

Working at a Ford Dealership in the 70s, we had a new Ford truck with a bad oil consumption problem.

We ran 30W oil to try to stem the use.

A Ford rep told us to use 10W40 and it would stop.

We didn't believe him but after 2 oil changes, it stopped using oil.

[Guest drnittler]

All the other parts are new including valves, seat, stem seals, etc. I will hope I luck out. Thanks. Why did 10w 40 oil make a difference?

[Coley]

He couldn't really give us a reason, but it worked.

[Guest drnittler]

OK. It is hard to figure.