Deciding on which weight diesel oil for 2000 7.3L Ford Diesel

Whatever weight oil you decide on make sure zinc and phosphorus PPM levels are above 1200.. and that it has a detergent package of at least 2,000 PPM..

Personally I don't think you can beat Shell Rotella products for diesels.. or flat tappet engines..
Also, International originally designed this engine to use 10w30. I read this in an article about the Ford/International partnership for the 7.3L diesel.

You are correct about this. Caterpillar and Navistar collaborated to design the HEUI fuel system. I’ve worked for a Cat dealer for years, and we’ve always recommended 10w-30 for the HEUI engines even back when we used 15w-40 on everything else. You want that high pressure oil pump (which is an axial piston pump) to receive oil supply quickly upon cold start. Since we’re in Canada, 10w-30 is what we now use almost exclusively. But somehow most people seem to think a diesel engine “needs” 15w-40. IMO what is more important in these particular engines than grade is regular changes. The fuel system components are not cheap, and sooty, abrasive oil WILL cause failures therefore I’d recommend 5k mile changes. Straight from Cat (these are all HEUI engine models):

That being said, in your climate it probably wouldn’t make any difference. I don’t recall any specific problems CAUSED by 15w-40 in these engines. But you can confidently run 10w-30.


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