Is it ok to use 5w40 Mobil 1 TDT in the 997.2 Turbo DFI engine? I always used this in my 2004 996 TT and my 2009 997 TT but wasn't sure with DFI engine.

 

I’m using Mobil 1 5w50 in my 997.1, but I live in Auckland, NZ, and we never see temps below about 4°C where I am. If I did I’d be using 0w40.

List of approved oils as of 2 years ago is here: https://rennlist.com/forums/996-foru...ge-change.html

 

That oil is not an approved oil for any Porsche vehicle including its diesel engine vehicles. (IIRC Mobil 1 5w-30 is the factory fill for diesel Porsches.) Mobil 1 5W-40 TDT oil has a mineral oil component.

There are a number of approved oils to chose from. Any approved oil should have "A40" on the bottle/can. ("A30" I think signals the oil is approved to be used in its diesel engines.)

Whichever approved oil you use be sure you select one that has the proper viscosity for where you live/drive. Porsche says to use 0w-40 in cold temperatures (-25C). I'd be tempted to use 0w-40 even if the temperature didn't get that cold but did dip below 32F a lot.

 

A few years ago on another forum, someone wrote to Mobil requesting information on which of the Mobile 1 oils (viscosity ranges) had the most durable/stabil additive package in regard to long term use. Their reply: 0W-40. Interesting that it wasn't one of the narrower-range oils, like 5W-30, etc.