[cnavarro]

You just have to be knowlegable about lubricant choices, that's all.

Mobil's Delvac 1 isn't formulated for limited slip differentials. And yes, they do make a GL4, but again, it's not something found at your FLAPS.

As far as drain intervals, if you ask a performance transmission builder that does Porsche gear boxes, I'm sure they'll tell you to change the gear lube more often than 100,000 mi. That's way too long. If you track the car, it should really be done at least every year. Same goes with the ATF on Tip cars if tracked.

If not tracked, I would take Porsche's recommendation and cut it in half, at the very minimum.

It's interesting to see manufacturers like Kia with their very good extended powertrain warranties and see on how short their drain intervals are.