First Rebuild - almost done - Oil question

[red63]

I just finished my first Porsche rebuild of a 3.8L engine on a dedicated track car. Great learning experience. This is a rookie question that might leave more experience posters groaning.

Engine is back in a started OK the first time (a small miracle). I put in approximately 8 quarts of oil to start. While warming up I had the oil filler cap off and about a half quart of oil gushed back out. This never happen prior to the rebuild when adding oil with a running engine.

I was using 15w-50 Mobil 1 prior to the rebuild and went with penziol dino 5w-40 after the build. A local mechanic suggestion stating I was wasting money with the synthetic on a fresh rebuild considering the next oil change will occur shortly. There might have been a quart of the synthetic in the cooler so a little oil mixing might have occured.

So three questions -

Will that small amount of synthetic mixed with dino cause a problem?

Anyone disagree with the oil grade?

And the big question - why the backing up of oil from the filler tube after only 8 quarts?

Thanks for the feedback.

[Eagledriver]

The mixing of oil will not be a problem. I think your grade of oil is fine for a break-in. Don't know why the oil backed up. Maybe that's all the oil it needs until the thermostat opens up for the cooler and the external cooler.

-Andy

[euro911sc]

Big bubble of air came out of the pipes leading to the tank and spattered oil out the opening?

Just a guess...

-Michael