gunlover05

Doing my first oil change soon and wondered about the oil in the oil cooler and lines that run to the front (85 Carrera)....does that dirty oil drain out, or is it left to mix with the new oil after a normal oil change (tank+case drain)?

ron mcatee

It is left to mix as you have no way to drain and flush the tank nor lines. Only way to get it all out is to remove the lines and oil cooler and completely flush the tank and lines. That's the way it's been done since I've been doing it (40 years on 911's). Good luck.

Mike Murphy

All the more reason to make sure that you change the oil at the proper interval and not switch oil brands/viscosity too often.

ked

no it doesn't all drain out (maybe a bit over a quart?) - it mixes w/ the new oil. good reason not to wait till your oil is completely filthy & broken down to change it. the rules of good oil management...
a) be sure to get the engine thoroughly warmed up as often as possible - drives out impurities.
b) oil change intervals vary according to usage.
c) when it doubt, change it (& keep records).
d) use the factory oil filter (I replace mine approx. 1/2 way through each oil change interval).

Mike Murphy

Also, I use a rag and clean out those oil plug drain magnets. That way, during the next oil change, you can see if your car is shedding any metal. Mine were both covered with a sludge. Hopefully, that metal sludge was there for many years and my car isn't shedding...

gunlover05

thought as much by looking at the oil system...glad I've got an oil cooler though, and I'll be changing it every 2K then....I don't drive that many miles/year anyhow....I dispise dirty oil

Brucechas

My mechanic's technique is to blow the residual oil out with an air hose...

gunlover05

blow out with an air hose? do you know where/how he does this?

Edgy01

Don't sweat it. It represents such a small amount that it's not an issue.

Mike Murphy

Well if the mechanic wants to go to such lengths, I certainly wouldn't stop him either...

velo5338

The Elephant Racing (finned) oil lines that I recently fitted to my '86 Carrera have a Schrader valve fitted to facilitate such blowing out of the lines.

Mike
'87 930
'86 Carrera

Mike Murphy

Mike, do you drive in cold weather?

SeattlePorsche

What I learned on my first engine drop is that there is a lot of residual oil stuck in the engine, and who know how much there is in the lines to the oil cooler. There is a thermostat back there that doesn't open unless the oil it hot, so it won't drain. Everytime I flipped the engine over or onto it's side you could count on more oil flowing out. The there was alot of oil in the oil cooler.

I realized it's not really an "oil change" but rather an dilution of dirty oil with 9 quarts or so of clean stuff. Seeing how easy it is to change the oil (as well as what an event it would be to rebuild an engine) I will change it every 3000 miles. My cam shaft #6 intake lobe as well as the rocker had moderate pitting damage (97k miles). Of course I am at least the 4th owner of the car so I don't know how good the previous owners were.

Edward

Perhaps a 1.5 - 2qt residual vs a total volume of ~12qts? Not at all worth thinking about, IMHO. The more important consideration is changing oil at proper intervals. Change the oil/filter and drive happy, really!!

Edward

theiceman

I am not sure how much I just took out of my car but I drove it until the car showed 190 degrees , then changed it after coming off the highway. hoping to catch the thermostat open. All I can say is that I put 11.75 quarts back in and the dipstick was on the full mark. Tells me I got as much out as I am going to get.