Okay I have to make a decision. I can't find Rotella Syn. 5w-40 CJ-4 which I want or Mobil 1 15w-40 Syn. CJ-4 which one is everyone running.

Only the BEST for me, Schaeffer's Supreme 9000 5w40... The Supreme 7000 15w40 is great oil too...

Rob

Okay I have to make a decision. I can't find Rotella Syn. 5w-40 CJ-4 which I want or Mobil 1 15w-40 Syn. CJ-4 which one is everyone running.
How many miles are you planning on running the oil before changing it?

5,000

I'd have to say that at that OCI interval, just about any conventional oil will hold up fine. Choose which ever you can find on sale. Jeez, for 5k miles, you could run Coastal CJ-4; I saw it at AAP for under $8/gallon, including tax!

Allow me to be the first to try and convince you that 5k mile OCI's are a waste of time/money. The Dmax is extremely easy on oil. There are lot's of UOA's that show you can easily go 7.5k miles, and even 10k miles on conventional oil. Running a synthetic can drive you out past that. If you're going to, or past, 10k miles, I'd strongly consider a Used Oil Analysis to confirm your oil's health.

BTW - I don't think there is a 15w-40 Mobil 1; there is a 5w-40 Mobil 1. I'm supprised you can't find any. Check Wally World? There is a strong rumor that if you find Mobil 5w-40 synthetic Truck and SUV, it's the same stuff, just bottled and packaged differently. I cannot assure you of that; I've not read the PDS. I'll try to find it here in the next day or so and attach a link if I can find them.

If you can hold out with dino oil for the summer in CJ-4 (any brand will do), then by the time winter rolls around, the new CJ-4 Rotella 5w-40 synthetic should be out everywhere. It's predecessor (CI-4+) is a top performing oil at a very reasonable price.

5,000
Save your money and go with a dino.

Rotella, Delo, Super Tech, Pennzoil, etc. will protect just as well as a synthetic. Unless you are seeing extremely cold temps or are sled pulling and running extremely hot temps, then a syn oil will provide minimal benefits.

You will not see better wear numbers from a syn -vs- a dino based oil. I've looked at way too many UOA's to confirm that. Syn oil is great for your front and rear end, but very seldom do people see any benefit from a syn oil in the engine. In your case, 5K OCI's is a complete waste of money (5K is too little for a dino or syn).

X 2

Thanks Guy's! In my 05' I ran the Rotella Syn. and changed it every 6,500-7,000 in the summer months when towing my boat(11,000 total). You are right I meant to say 5w-40 for the M1 not 15w-40.