# oil is dark



## phin (Jul 20, 2005)

Recently i 've noticed that after an oil change, the oil gets black within 2
to 3 weeks.IT does not seem to affect the performance of the car but i also
notice that my the number spark plug is blackened and wet too.The car
is obviously burning oil furiously!!!.Can anybody enlightened me. I have
a 91 stanza with 200k or more on it. Thanks


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## Asleep (Jan 19, 2003)

with that many miles, the rings could be going bad or the valve seal on that cylinder may be bad. if you do a compression check, youll know for sure. is there any smoke (blue) on startup or between shifts?


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## Bror Jace (Apr 26, 2003)

Or it could be that the fresh oil with a fresh additive package (detergents/dispersants) is cleaning up sludge and crud left behind by prior neglect.

And/or that your PCV system is clogged and is rapidly sludging up your motor.


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## phin (Jul 20, 2005)

NO there is no blue smoke and amazingly the car runs just fine.I did a compression test 2 years ago and it was fine.The car's performance is
remarquable considering the high mileage.I only wish i could get rid of
this black oil.What makes the engine burn oil?.This ka24e engine is the best 
engine ever made!!! and it will probably last forever


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## phin (Jul 20, 2005)

Pcv is clean.Could LEAKY INJECTORS BE THE CULPIT?


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## Bror Jace (Apr 26, 2003)

*phin*, take the PCV valve off and shake it. Does it rattle freely? If not, clean it with carb & choke spray ... or replace it with a new one.

Yes, leaky injectors could be the culprit as running rich or unburnt fuel _could_ get into the sump and some of this is very dark in color.

Oil is burned inside the engine when the cylinder walls get scored/scratched and oil gets into the combustion chambers or the valve and other seals start to give way and the oil gets in that way and is burned. A compression check suggests your rings and cylinder walls are in good shape and it's not a problem.

I don't recommend aggressive cleaning/flushing of engines which are running well. They (the solvent-based ones) can _cause_ wear under certain circumstances.

I'd use one of the 15W-40 oils like Chevron Delo400, Pennzoil Long Life 15W-40, etc ... as these dual gas/diesel oils have stronger additive packages to clean engines and keep them clean for a long time. Once cleaned out, feel free to go back to a 'normal' motor oil for ongoing use.

You might also add a couple ounces of Marvel Mystery oil to your crankcase a week before your next oil change. It is a mix of really light oil and some solvents. Might do a bit of cleaning and help you get a better drain ... without doing anything extreme.

And when you drain your oil, make sure the car is on level ground ... then jack up the far side about 12" with the plug out and you'll get a little extra oil out. Jack it up, let it down and repreat this 2-3 times. You should see a bit more (dirty) oil drain out. All that leaves will leave your new oil cleaner longer.


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