# Mystery engine oil use & consumption



## PONTIAC CLASS (Feb 4, 2014)

Has anyone used Lucas Engine Oil Stop Leak.
I have been told there is an invisible oil use taking place with my 389.
There is no smoke from exhaust pipes, no oil dripping, no oil in coolant.
The engine has a COMP CAM "THUMPER CAM" heads original and recent valve job. When idling there doesn't appear to be any oil consumed. When driven 50 miles or so at normal speed range the engine uses about 1/2 quart of oil.
I am using 10/40 conventional valvoline. Is the oil being used through the valve guides. Again, there is no visible smoke from exhaust.
The engine has 1,650 miles and had the following completed. Note: the pistons main bearings, crank shaft were left untouched and remain factory original.
New oil pump, new timing chain, heads completed and heads "decked".
Engine runs strong, etc.
Also, with the factory cam there was no oil being used.
If an engine sits for a long time will the piston rings develop problems,and if the piston rings are part of the problem would smoke from the exhaust be evident.


----------



## 05GTO (Oct 6, 2004)

Have you checked the PCV valve, if it is plugged or missing that could cause high engine pressure and excessive oil consumption.


----------



## geeteeohguy (Feb 2, 2008)

Pull a spark plug and have a look. That will let you know if the engine is indeed burning oil. Any leaks? Pull the breather cap when the engine is running and look for oil smoke/vapor. This would indicate worn rings/excessive blowby. From a cruise speed, downshift into a lower gear with a buddy in a car following you. Smoke from the exhaust on de-cel indicates worn valve guides/seals.


----------



## PONTIAC CLASS (Feb 4, 2014)

*I Will Follow Up With Your Suggestions*

Thanks gentlemen - I 'll check the PCV valve for it working properly.
About the "smoke - blow-by" with breather cap off - should any smoke, vapor or visible blow-by be seen coming out of valve cover opening? Are there "degree's of blow-by smoke"? I would imagine that "blow-by" is progressive and becomes worse over time? 
This 389 engine has 122,900 miles with original pistons and rings. The pistons are flat surface.
Would an aggressive cam be a factor?


----------



## PontiacJim (Dec 29, 2012)

PONTIAC CLASS said:


> Thanks gentlemen - I 'll check the PCV valve for it working properly.
> About the "smoke - blow-by" with breather cap off - should any smoke, vapor or visible blow-by be seen coming out of valve cover opening? Are there "degree's of blow-by smoke"? I would imagine that "blow-by" is progressive and becomes worse over time?
> This 389 engine has 122,900 miles with original pistons and rings. The pistons are flat surface.
> Would an aggressive cam be a factor?


Could be a number of things or combination there of. So here are a few things to consider. 

The heads could be a problem. Did you get new bronze valve guides or did your shop knurl the guides? Do you know if the shop used the O-ring seals that fit in the valve retainers? Did they re-install the oil shield that goes under the valve retainer and over the springs? -Most shops leave these off as they can get in the way on a high lift cam, but they can help keep oil off the valve stems. Did they install Viton or Teflon positive valve seals? This requires some machining, but helps oil control on the valve stems.

I did a set of heads up (and wanted to save money) and the machinist knurled some of the valve guides, and I installed the O-ring type valve seals at the retainer, and left off the metal oil shields. I used up oil and my engine was rebuilt -I had the intake manifold off at one point and could see a build-up of burned oil on the valve stems, so knew oil was getting down the valve stem more than it should have, and I didn't have any visible signs of burning oil. So this _*might*_ be some of the problem, but it also may not be.

Could be the rings. Perform a compression check with a compression tester. Note your readings. The Pontiac manual then says to squirt 30CC's of oil in the cylinder and retest. If the readings improve, then bad rings or cracked piston. 

Your cam may be aggravating the problem of worn rings. Some cams develop more dynamic compression based on the Lobe Separation Angle (LSA). So, more pressure built up in the cylinders may be too much for the old rings to handle. 

A vacuum gauge would be your next test. If you have a fluctuating needle as engine speed is increased, you might have a bad head gasket.

It could be none of these things, but this gives you a few items to consider.


----------



## Rukee (Feb 8, 2007)

Is the valley pan baffled? Or aftermarket?
When I first got mine, it had a broken piston between the second and third rings so it passed a compression test but burned oil.


----------



## BearGFR (Aug 25, 2008)

Which heads are you running, and have they been ported?

Bear


----------



## geeteeohguy (Feb 2, 2008)

Now it comes out. 123k on an original high compression 389. Here's your next step: get a leakdown tester and run a leakdown test. My bet is that you have broken piston lands or borken piston rings or both. Or possible stuck rings. It is very common to have broken piston lands/rings in these old high compression 389's that have been run on any fuel less than 98-100 octane. They will ping and detonate at a frequency you can not hear and destroy themselves. I hope this is not the case here, but again, you NEED to do a leakdown test. BTDT on these engines. BTW, ANY visible smoke out of the breather=worn engine.


----------



## PONTIAC CLASS (Feb 4, 2014)

*Thanks for all responses*

I have some homework to get done now but getting a handle on what is going on or potentially going on in my estimation is at least 80% of the solution.

http://www.gtoforum.com/images/smilies/wink2.gif.pagespeed.ce.L6aiHcjVkG.gif


----------

