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Weak Cylinder

My 98 Mazda Protege has a weak cylinder. #3 cylinder is at 85. The car runs excellent though. The only thing is is that when it gets cold (60 degrees F. and below)outside it smokes/burns oil when I first start it up for about 10-15 seconds.

Can anyone explain why?

And do you guys think it would be worth it to try Lucas oil stabilizer on this engine?

The valve guides may be worn and allowing oil to seep down into the cylinders when the engine is turned off. When you start the engine, the oil is then burned in the combustion chamber. New valve stem seals may cure this condition. However, if you have low compression in one cylinder, it may not make sense to have the valve stem seals replaced. You didn’t say how many miles are on your car, but it probably isn’t cost effective to put a lot of money into a 13 year old car. I would just keep driving it.

It also might be that that cylinder needs to have its valve clearance adjusted.
If the valve clearances are too tight, then you will get a lower compression reading, if any at all, under extreme circumstances.


Thanks for the replies guys.

When I had the compression test done the mechanic put some oil in the chamber with the low compression and the compression came up. The mechanic said that that meant the piston ring was the problem. He also told me to use STP Oil Treatment but recently someone told me that Lucas is better. After reading about additives on this site I’m not sure any additive is the way to go.