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Q: antifreeze in motor oil ( Answered,   1 Comment )
Subject: antifreeze in motor oil
Category: Miscellaneous
Asked by: jboo-ga
List Price: $10.00
Posted: 16 Oct 2002 08:25 PDT
Expires: 15 Nov 2002 07:25 PST
Question ID: 77287
What does antifreeze in your oil do to a motor (BMW 735i)
Subject: Re: antifreeze in motor oil
Answered By: bcguide-ga on 16 Oct 2002 09:03 PDT

Antifreeze contains glycol. Glycol breaks down at high temperatures
and when it cools back down it forms clumps.

Antifreeze in your motor oil creates a lot of sludge very quickly.
When sludge builds up, the oil strainer gets clogged. The clogged
strainer prevents oil from getting to the motor (oil starvation). You
know that oil acts as a lubricant to the metal parts of your engine.
When there isn't enough oil, you’ll get metal-to-metal contact.

The friction this produces wears down the metal parts. If it gets bad
enough - and hot enough - the moving part will get fused together -the
engine will seize. Once it seizes, you’ll have to rebuild or replace

If you think you have antifreeze in your oil, get the oil changed.
Don't wait to see if you'll have a problem. By the time you find out,
you'll be paying a BMV mechanic a lot of money to put a new engine in
your very nice car.

Some sites that explain this are:
"As engine temperature rises, so does the probability that the
glycol/oil mixture will approach solidification."
"Example: during a routine valve cover gasket replacement, antifreeze
could accidentally run or drip into the oil, creating large amounts of
sludge very rapidly."
"Glycol, as found in engine coolant, when mixed with motor oil
(including synthetics) will greatly increase the chances of engine
"Coolant Contamination -- Cooling system leakage is one of the most
serious hazards for engine lubrication. One alternative test measures
the level of glycol in the oil, while emission spectroscopy will
detect levels of boron or sodium from the additives in antifreeze. In
either case, once coolant leakage is detected, the leak should be
repaired and the oil changed."
"Antifreeze is an insidious bearing destroyer. When the oil is hot,
the antifreeze mixes congenially causing no appreciable problems. When
the oil is cold, the antifreeze will coagulate into clumps. If this
coagulation happens inside a bearing, say bye bye."

Notice that these sites cover car, boat and motorcycle engines...

search terms: antifreeze motor oil engine sludge

Get your oil changed... fast!

Good luck and happy searching,

Request for Answer Clarification by jboo-ga on 16 Oct 2002 10:12 PDT
The antifreeze is of ethylene glycol base does that make it better or
worst,how long and how ethylene glyol does it take to hurt?

Clarification of Answer by bcguide-ga on 16 Oct 2002 19:37 PDT
Hi bobthedispatcher-ga,

Most antifreeze contains ethylene glycol. How long it will take to
destroy your engine depends on how much is in the oil, how much you
drive, how hot your engine gets, and other factors. I can't give you a
specific time frame for how long it will take to trash your engine. I
would flush the oil and replace it immediately. Why take a chance on
having to replace your engine instead of your oil?


Clarification of Answer by bcguide-ga on 16 Oct 2002 19:40 PDT
The day is too long :-)

The clarification was to you, jboo-ga, not to bobthedispatcher-ga. I
cut and pasted the wrong name... and noticed it as I hit send.

Sorry for the confusion!

Subject: Re: antifreeze in motor oil
From: bobthedispatcher-ga on 16 Oct 2002 12:13 PDT
Water/antifreeze in the oil is frequently caused by a head gasket
leak. It should be checked properly - after changing the oil you need
to frequently recheck the oil, it may become foamy, or whitish colored
from further contamination if there is a leak.  Other signs of a head
gasket problem include unexplained loss of coolant, oil in the
radiator, overheating, and excessive water vapor in the exhaust (some
is normal, from the catalytic converter!)

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