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Re: oil jelling

Phil Rose mentioned, about oil jelling and synthetic's protection 
from it...

> I wasn't aware of this "jelling" propensity of oil under overheat
> conditions. How hot, how long I wonder?  Does it form a permanent, thick
> gel? My son's '91 droF Aerostar is in the shop at this moment because of
> oil pressure problems. Last month he noted low oil pressure, although the
> oil level was OK.  A few days later at the oil change, no oil would drain
> because of a heavy gel at the bottom of the crankcase. It was blown away
> with air pressure, the oil drained and a flush was done. But the low oil
> pressure problems persisted--leading to engine noise. Engine is now being
> pulled to look at oil pump, etc.
> We were at a loss to understand how such a thick gunk could have formed.
> The van has about 120K miles now, and was bought with 40K miles on the odo.

Phil, I don't know the exact temp tolerances or how long oil must be 
subjected to them to cause jelling.  .  I have heard more than once 
that excessive heat - VERY excessive - can cause oil to jell.  At 
that point, the pump won't move it - engine fails.

The only time I have seen oil do this was in a 78 ford 305 driven 45 
miles up a 2000 foot grade with almost no water.  It had gotten so 
hot there were little balls of bearing babbitt material rolling 
around in the pan!! The oil was jello.

If this has happened in the engine you mention, I'd plan on a total 
teardown - you need to check every bearing in it, as well as making 
sure the heads are not warped, etc.  I know etter because 
YOU'RE involved, but otherwise I would suspect your son has 
tried to drive forever without changing the oil.

That leads me to think you better check the temperature sensor and 
gauge - as they may not be telling the truth!

Al Powell, PhD             Ph:  409/845-2807
Ag Communications          Fax: 409/862-1202
Texas A&M University