I'm curious to hear from folks who run Mobile 1 5w40 TDT oil in their 5.4l gas (2v) trucks.

Why did you choose to run this specific oil?
What have been your observations running this over time (mutliple oil changes)?

Not really interested in a should I/shouldn't I conversation.

 

I've been running the 5w40 Rotella synthetic for awhile.
I choose the diesel spec oil because of the better additives package.
JL

 

I run the M1 5w40 TDT in my blown 5.0L DOHC engine (in one of my cars). I was running M1 5W30, but switched to the 5W40 TDT for the better additive pack and for slightly increased hot oil pressure. The only observation I've had is that it did exactly what I wanted it to do, it raised my hot oil pressure a bit.

-Rod

 

That is awful thick for a Modular engine. Not good for cold start-ups.

 

You've got your numbers switched around. If it was a 20W40, it would be very thick on cold startups. A 5W40 is going to be just as thick when cold as a 5W30.

-Rod

 

I would stick with something in the 5w-20 or 5w-30 range. I've heard going to a heavier oil can cause the valve train to be starved and increase wear.