Maxx1

I don't know, I kind of agree with your thinking. I notice after a long stop light with the car at idle, the oil temp starts slowly creeping upwards, then even underway it takes a long time on the highway to scrub any of that heat off. I just make sure I stay off boost for 3-5 minutes before I park the car.

Something I noticed concerns me. My car used to come on boost gradually as if I slowly step into the trottle. Lately it's like a on-off switch..... as if the turbo is sticking and then suddenly starts spinning when the force of exhaust is strong enough. Is this a typical condition on some turbos or perhaps turbos that haven't been cooled down properly?

DonE

Don't get engine temp confused with turbo temp. At the end of a drive, you idle the car to lower the exhaust temp which lowers the temp of the turbine housing. When tooling around town, the exhaust gases can be between 1000 and 1200 degrees F. At an idle, I've measured mine at 325F. By the time these gases make it to the turbine, they are most likely cooler. While you are at idle waiting to cool the turbo, the 220F oil is bathing the bearings, again cooling the center section. This is why idling after a drive is so important.

The engine temp will rise because no air is cooling the oil or engine. But here, we are only talking about raising the temp from 210F to 230F - still a long way off from exhaust temps.

This is a classic example of why synthetic oil is superior in these cars (OMG, sorry for bringing oil opinions to this thread) - higher flash and boiling points.

Maxx1 - you could be experiencing coking of the turbo shaft. Its sluggish until high RPM and oil pressure force the turbine to finally spin at its designed RPM (something like 98,000rpm on a K27).

Benjemin Bale

I do the same as most everyone else, just drive it easy the last leg of my trip and let the car idle while I get the garage open, pop the deck lid and let it cool untill I return to the garage. I wasnt used to how warm these air cooled motors run, but thats just one more way that they are unlike American cars..... It adds to the experience, by the way glad to see you have your fouling problem fixed.

911rudy

I just read an answer to a question about oil additives and cooling in our engines and it discussed idling the engine. It is bad for our engines to idle for extended periods due to the poor top end oil flow at low rpm. As mentioned above, by Maxx, you will see the oil temp start to go up at idle so any period at idle should be no more than a couple of minutes. I was WRONG to compare a water cooled engine to an oil/air cooled engine because the low oil flow cannot provide enough cooling capacity to keep a stabilized temp. In a water cooled engine the radiator and fan are enough to keep it stable and below a harmful temp. It said that on 996 and later engines the top end oil flow had been improved. DonE is right about the turbo and a short idle is still best for cooling/lubing the turbo bearings before shutdown. It looks like an electric oil circulation pump would provide the best of both worlds.

Maxx1

What do you mean, coking? ...as in burnt oil gumming the shaft up?

911rudy

Yep.