Source for CJ-4 diesel oil………

Rotella T1 is still available at Walmart last time I checked.  Rural King carries Delvac 1630 which is a diesel 30wt engine oil.  They are only rated CF-4, but is a 30wt diesel engine oil.  I don't recall CJ-4 ever being available in a straight weight oil (it may not be possible to meet the specs without being a multi-weight oil).

going to be hard to find a CJ4 oil in straight 30wt as Hurst said..... Lots of options if you go to 10- 30 or 15- 40 .........I know what your book says, but is 35 years old.... Maybe UPGRADE to a 15w-40  ??

Edited by steve(ill) - 06 Nov 2024 at 1:44pm

We serviced lots of those engines in our shop. International dealership. All went down the road with 15-40. Most in school bus application.

Edited by Ed (Ont) - 06 Nov 2024 at 2:48pm

Agree with all the above, multigrade can only ever be an upgrade in my opinion. Easier cold starting/better cold oil flow coupled with higher stability when the temperatures get up there.

Edited by ekjdm14 - 07 Nov 2024 at 8:05am

Not sure what or if it's still even available, but my policy has always been to run the cheapest "known brand" (i.e. not just random ulong dingdong Amazon brand, usually use Mannol) but it's likely got some kind of detergent package I suppose anyway.  My thinking is that more expensive oils probably have more/better detergents. (The amount of sludge in some modern engines suggests cheaper oils don't have as much anyway)

Normally a "NEWER OIL" will be backward  Compatable...

rottello t4 15w-40 will work just fine  you probley will not find what you are looking for at the dealerships anyways  like paul b says  t4 still has about the most zinc  our shop uses shell or valvoline  we also use it in all our older gas engines and our gas tractors because of the higher zinc done us good for many years  

Lars(wi) wrote: Other than going to a farm implement stealership, I’m trying to get some 30w CJ-4 engine oil. Recently acquired a 1991 F-350 w/7.3 IHC engine. Ford and Navistar still call for straight 30 weight for temps above 0* F. for this particular engine. We don’t have any co-ops, or Farm & Ranch supply stores that stock it. No Case/IH dealerships that I know of, to get IH #1 oil.

IH IDI, use 15-40 year round with some Lucas stabilizer in it and keep a gallon jug of top off in the truck. I've been running IDI's and wrenching in then for awhile. Rotella T4 has been known to burn a little faster in them, so I normally run Delvac. Rotella T6 is about the best all round diesel oil when considering the price point as a factor.

Most important thing with them is to keep the fuel system sealed up. I delete all of the "olive" seals in the fuel system. If you do that, replace the return line caps and o-rings with viton o-rings and are still having some air intrusion, go to a 1 piece fuel filter/separator and delete the filter head preheater while you're in there. Most don't work and are a common intrusion point. As for fuel parts, best bet is Justin Anderson/IDI Performance. We just lost Russ of Russ Repair here recently and IMHO, other than being a great guy, he was a bit better on the customer service side of things and a touch cheaper on rebuilt injectors without cutting any corners.

Edited by Clayfoot - 10 Nov 2024 at 10:49am

If you don't mind spending the $$, grab the royal purple. I always recommend getting a PSD oil filter as well so you get that extra quart of oil in there got the extra cooling/heat soak capacity. Easier to get ahold of to remove when you changed it too, not to mention is typically available on the shelf. Same threads on the filter as the IDI filter.