oil temp hit 260 degrees , whats the best synethic oil

10-30 may be approved, but my 2014 F350 diesel owners manual said to use 5w-40 for severe duty, which was defined as towing.
I used Rotella T5 15W-40 synthetic blend in my 2016 Ram. Might go to T6 5w-40 in the 2018.

Gearitis wrote:
Motorcraft 10w30 Diesel Oil synthetic blend is not CK-4 spec. And according to Ford and their official statement, do NOT use CK-4 in Powerstrokes, new or old as CJ-4 give better lubrication.

Clicky

That has changed since CK4 first came out. Here is the latest list I could find of Ford approved oils including CK4. Ford Approved

I've been using Schaeffer's Oil for years, and really think it is a quality product Schaeffers

Delo 400 15W-40. Change oil every 6 months as I do not hit 15K before that, per RAM guidance. Chris

Me Again wrote:
What does your Ford dealer have to say about those numbers? Or ask Fish.

What oil do you use?


chevman Rotella 5/40 full synthetic for our chebby

1950panman wrote:
2005 ram 3500, cummings i have not change the oil yet, just bought this truck with 72,000 miles it does have.... 15 40.. on the sticker for next change,,,any similar commits>? lane ty in advance

Stick to 15-40, AMZ/OIL still sells the non LE Diesel Marine 15-40. I used to run 10k in my 98 12V with FleetGuard Stratapore filter every 5K. Blackstone said I could go longer.

2005 ram 3500, cummings i have not change the oil yet, just bought this truck with 72,000 miles it does have.... 15 40.. on the sticker for next change,,,any similar commits>? lane ty in advance

Motorcraft 10w30 Diesel Oil synthetic blend is not CK-4 spec. And according to Ford and their official statement, do NOT use CK-4 in Powerstrokes, new or old as CJ-4 give better lubrication.

Clicky

What does your Ford dealer have to say about those numbers? Or ask Fish.

Puddles wrote:

theoldwizard1 wrote:
Motorcraft Super Duty 10W-30 Diesel Engine Oil is sold at Walmart for under $20. It is API certified CK-4.

Even the old non-synthetic transmission fluid was good for over 250F.

Did you mean CJ4 ?

Nope. CK-4 is the "top of the heap" for diesel oil at the moment.

API Service Category CK-4 describes oils for use in high-speed four-stroke cycle diesel engines designed to meet 2017 model year on-highway and Tier 4 non-road exhaust emission standards as well as for previous model year diesel engines.
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API CK-4 oils exceed the performance criteria of API CJ-4, CI-4 with CI-4 PLUS, CI-4, and CH-4 and can effectively lubricate engines calling for those API Service Categories.