What happens if oil overfilled?

[Peter]

overfilling

Here's what I've heard, but I don't know if some or any of it is true. Overfilling may: lead to leaks from seals and gaskets, may wreck some of the gaskets, may lead to foaming of the oil which can push oil into the intake, may cause higher pressures and excess vapours in engine crankcase. Will a couple of hours do it? I don't know, but I wouldn't risk it.Peter

 

[Dave]

When I changed the oil for the first time on my Cat 30, I refilled with less than the capacity in the manual but still ended up about half a quart over. I had to return with the vacuum oil changer and remove the extra. There is a CAUTION about overfilling but I've never been clear on what the potential damage is from an overfill. If an engine runs for a few hours with some extra after an oil change what is the potential for damage?

 

[J Simmonds]

What I have heard.

I have never run the engine in an overfill postion but I have been advised that you will have a GREAT DEAL of difficulty in shutting down. Best to drain some off. JS

 

[Merrythought]

Overfilling Oil

I have been told by reputable marine engine servicers that overfilling on oil can cause a runaway engine. Having experienced a runaway engine on my previous boat, I can say it is not a pleasant experience and caused me to have that particular engine rebuilt.

 

[Paul]

Possibly blown gaskets/seals

In a car, overfilling the oil can lead to excess oil pressure that may cause gasket or seals to blow. Of course, it depends on the amount of overage. For instance, I don't think 1/4 a quart in a 5 quart capacity engine would produce excess pressure sufficient to blow gaskets. But, why take the risk. I recommend pumping out the excess.