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piston blow back

66Alpine

Donation Time
hi everyone,

I am almost ready to crank up the 66, but i am miffed about one thing.. I have put maybe 100 miles on the car in 5 yrs..the oil is black and I have changed it 3x..still black..why isn't it golden honey in color? someone mentioned probably engine blowback..what the H is that? and how to correct..

Thank you,

Johnny
 

RootesRacer

Donation Time
You are thinking of "blow by", which is caused by a lack of sealing of the compression rings.

Worn engines, or engines with broken compression rings offer little sealing against combustion gasses when running, the result is carbon contamination of the oil.

An engine is such condition will usually smoke under pretty much all conditions, as well as leak oil due to high crankcase pressures.

You should do a compression check to verify this condition.
 

66Alpine

Donation Time
piston blowby

Thank you very much for your quick response.. I will check the compression as soon as I can borrow the gauge..

Johnny
 

Bill Blue

Platinum Level Sponsor
In addition, some oils turn black after very little use. "Back in the day", Shell oils were notorious for that. Don't know about modern oils. Also, an engine that is running very rich can cause the oil to blacken.

If you want honey colored oil, consider switching to propane. A big problem with running propane is the rig always smells like a hot cook stove, leading to continuous hunger.

Bill
 

RootesRich

Donation Time
The fact your oil is "black" may not be bad thing. In fact, many oils will turn black within a couple of hours or driving just from the additives burning off. The only way to verify an oil's lubricating value or contamination level is through Spectrographic oil analysis.

My Dad has a PhD in Chemical Engineering and worked for Chevron Research for 30+ years. I'm sure he'd be pleased to know that some of the automotive/ chemical knowledge he tried to drill into my head during my teenage years actually stuck. :eek:
 
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