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Oil Overfill Damage?


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high level of oil will cause for foaming due to the churning of the oil by the crank journals....the comment "should I have an oil change" leads me to believe you farm out your routine maintenance also.  So yes, an oil change would correct this...else you can just drain a bit out now and wait for the scheduled oil change.  

Edited by Plymouthy Adams
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One quart extra won't damage an engine.

However it might lower your power and fuel economy.


There are certain diesel pickup trucks which shall remain nameless, that inject fuel on the exhaust stroke periodically to heat up and clean their trap oxidizer.

These engines routinely have fuel washing down into the their crankcases raising the oil to alarming levels. One gallon extra is not unheard of!


I once bought a car with a sheared off oil pump drive shaft...it was in Lancaster-Palmdale and since I didn't own a trailer, I had to drive it home to Burbank, CA.

90 miles at 65-70 mph. So I just put in two extra quarts of oil and hoped for the best. I made it without any drama. Pulled the engine and removed the pan and there was nothing wrong except the pump shaft! A new oil pump ( for insurance ) and drive shaft and put it back on the road. The two quarts extra were 50% more oil than it was supposed to have ( 4 vs 6 ) so I figured that was a good ratio.


Model A Fords will leak oil if parked on a steep driveway nose up. The only solution is to back in.

Model T Fords have no oil pump or "dippers" on their connecting rods so you don't want to park them nose up in a steep driveway and let them idle for extended periods.

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Good point on the engines cylinder location.


I worked with a guy once who rented a car for a weekend trip about 300 miles away.

Turns out the rental agency did a oil change without draining the oil ..... the kid just added the fresh oil on top of old.

They drove about 100 miles & the engine blew up. ... 5 extra quarts is a lot of oil.


But the side mounted cylinders in the suburoo ??? .... I would want to drain it out or only drive it straight to a oil change facility & correct it.

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I had a customer once that had a check engine light on right after a oil change.

The check engine light code was related to the variable valve timing.

Problem was caused by too much oil being whipped up by the crankshaft.

Air  entrained oil was getting into the variable valve timing solenoid causing erractic cam phasing. ECM turned the check engine  light on.

The fix..drain out the excess oil...don't over fill the engine oil!

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My uncle who was up in years always changed his own oil often.

But the memory loss with age finally caught up with him and one time while heading out for a trip back east with his and wife's latter 70's (per my Old memory) Toyota motorhome stopped for a night at a camp ground and he decided to change the motor oil.


The next day (a Saturday afternoon) out on I 80 near no towns the motor began smoking big time.  They really had not traveled far, but I guess too much!

They were able to finally get towed to the next small town where the only repair shop was closed for the weekend. At least they were in a motorhome.


Come Monday morning the mechanic diagnosed the motor problem.


My uncle had not Drained the old oil before he added the new 4-5 qts. of new oil!!


Mechanic drained all the oil and changed filter and replaced and all was well again after some run time to clear out LOTS of smoke the motor and exhaust system were finally clean.

No long term damage.





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For more time to waste lets read "Bob is the oil guy"...

Then debate oil grades, weights and intervals🤣

But first answer the op's question to his satisfaction!

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6 minutes ago, Dodgeb4ya said:

But first answer the op's question to his satisfaction!

That is a tough one ... 1 extra quart in my 49 dodge .... probably not worth the effort to drain it out. Probably leak it or burn it with a trip to town.


A 6 year old vehicle with a boxer engine what would happen with a extra quart of oil?

Subaru Boxer Engine Explained | Sport Subaru

I'm not sure I'm brave enough to find out. Could be nothing, could be something ...... I would correct it just as quickly as possible.

They hold the usual 5.1 quart oil capacity. How deep is the pan? Typically new vehicles make them as slim or small as possible.


While I do not know the correct answer ...... weighing risk & reward over such a trivial item as a oil change is not worth it.

If the owner is not physically wanting to change the oil, then take it to someone who will.

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If it was me I'd spend 15 minutes...reach up there at the rear passenger side of the pan...carefully remove the drain un just enough to drain out the excess oil.

Re-check the  oil level. Make sure it's right at the full mark or a tad below.

The owners manual all 1" of it probably will say..."Do Not Over Fill"...

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Well, after thinking over the advice here, I decided to get an oil change this morning. I hit two places that were booked far out. But one of them offered to "suck" one quart of oil out of the oil pan. So he did. Cost me $18.00.  I was very happy with that and the guy was very nice.


I don't know why that other car dealer said an extra quart wouldn't hurt - another mechanic said basically the same thing - but two of them did mention the foaming inside the engine.  


So thanks folks for the sound advice. You probably saved my engine.

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