Question about synthetic motor oil in my 6.0L
 

It's time for an oil change and I am thinking about changing over to synthetic oil. PLEASE DON'T turn this thread into an oil brand war. I simply want to make sure that a 5w-40 synthetic oil will be fine for the midwest summer months while we tow our 8,000 lb trailer. We plan to take several extended trips and I have been changing my own oil at the 5,000 mile mark. Thanks for your thoughts.

I just recently switched to Mobil 1 Turbo Diesel Truck 5w-40 Synthetic and instantly noticed easier starts and quieter at idle.

I'm sure I will really be able to tell the difference when the cold weather comes. I was previously using DELO 400 15-40, I've got 65k on my truck. I say go for it!

06 -250 here and I want to know about the Summer months in Hell with a zip code I mean Phoenix AZ is 5W-40 the right synthetic for me to use I pull A heavy rigg as well

5W-40 and 15W-40 have the same high temp viscosity rating as in the 40 designation. Synthetic also tends to coke less at higher temps such as in the turbo than dino oil. the lower number designation is the viscosity rating when cold thus the 5W gives easier starting in cold temps. I think the syn. is a good choice if the cost does not bother you. You still should do 5,000 mile oil changes.

Many people run 5w-30 rated diesel oil, towing and all, so with a 5w-40 you'll be fine.

Guys thank you I will get to it then. One thing I was told with these 6.0'S that i should do a change every 3 to 4K miles or 250 Gallons of fuel used or 250 engine hours witch ever comes first so is 5K to many Miles?

5k is fine with a good synthetic as long as there isn't too much idle time and short trips.

Thanks for the reply's guys. I'm gonna change to the 5w-40 synthetic later today.

I don't believe I have ever seen a diesel rated 5W-30 oil, there also seem to be few 10w-30s rated for diesels.

AMSOIL - Series 3000 Synthetic 5W-30 Heavy-Duty Diesel Oil (HDD)

From what I've read on the forums, there's quite a few people running this, even down in Texas where it gets HOT.

Amsoil? I guess I still hav'nt seen a diesel rated 5W-30 oil :-X05

I don't use any Amsoil products myself, but my next gear oil change will be to their Severe Gear oil, it cleans up in comparisons. Also, their 5w-30 oil is a VERY good oil. Please don't turn this into another ignorant Amsoil-hating thread.

No ignorance, I will keep it factual.

No Ford or International viscosity charts recommend or suggest the use of 5W-30 motor oil at temperatures above 30 degrees in their diesel engines.
Amsoil carefully words their application language such as below, note was it says and what it does not really say;

"is recommended for diesel engines and other applications requiring any of the listed worldwide specifications and gasoline engines requiring API SL, SJ, SH . . . or ACEA A3.

I'm from TX an ran the Rotella Syn. 5w-40 for 3 oil changes (15k miles) and each and every time when I would reach ~4k miles the injectors would get real loud at idle. When I would drain this oil it would drain out like water and the oil felt like it was a very low viscosity.

I went back to running Delvac 15w-40 with 2 quarts Mobil TDT 5w-40 and no more loud injectors. I got 102k miles on this truck and decided this will be the oil I'll run from here on.