John D. S.

RTFM

Libast

Except they designed the car and engine with a certain oil, and then wrote that in the manual. its unlikely the engine is going to call for anything different in the future

badabing

1. I have a 987.2 CS that is extensively tracked for the last 4 years. I run Mobil1 0W-40. I send a sample of every oil change to Blackstone. At this point I have about 15 consecutive reports. They all say the same thing. Oil is in good shapes. Minimal wear. Run the oil longer and beat the engine harder.

I use this oil because it's approved and it's readily available from Amazon and Walmart for $25 / 5 qts or less. I can do an oil change for less than $50.

2. As far as manual's changing or being wrong, the manual for my 1996 993TT calls for Mobil1 5W-30. The formulation on Mobil1 5W-30 from 23 year's ago is way different than today. That oil is no longer appropriate. So it possible.