Oil for 40-year-old UJM?

[ChuckTotaro]

Good old fashioned diesel oil works great in these classics. There is mo reason to overthink this.

Always used Rotella in my 1975 Honda CB550 with great results. However, Shell has changed formula for Rotella T4 from 100% mineral oil to a synthetic blend. Synthetic not good with wet clutch. What is a good aternative to Rotella??

 

[cheesepuffs2]

Always used Rotella in my 1975 Honda CB550 with great results. However, Shell has changed formula for Rotella T4 from 100% mineral oil to a synthetic blend. Synthetic not good with wet clutch. What is a good aternative to Rotella??

Valvoline's regular 4T motorcycle oil (blue bottle) or Castrol Go.

 

[Rygrego]

Are there any MA2 oils, 10W-40 (or close), that have ZDDP levels in the 1200+ range?

Bike is a KZ1100A (shaft drive) with high compression pistons, coming off a fresh rebuild.

It used to be that Rotella served this crowd nicely, but the new formulas have much lower ZDDP now, and people complain about shearing out of grade, and poor shift performance after a couple thousand miles.

Price is not primary driver, but it never hurts.

I have used just about any diesel 15w-40 synthetic without the low emissions rating. But I now run Mobil 1 15w-50 as it's ZDDP is higher.

 

[Bonz]

I'm going to take a stab at the recommended OCI on the stock KZ 1000 40-Year-Old ujm. It probably was 2,500 to 3,000 mi.

An air-cooled engine is a different beast than liquid cooled. Much looser tolerances between everything in the top end with respect to cylinders, pistons, rings. Oil contamination with byproducts of combustion (blow by) is going to be much higher, engine heat breaks down oil faster, etc.

IMO and IME (from experience with 40+ year old ujm's of the same era) you are going to want to be changing the oil much sooner than a modern engine regardless of the engine build. The oil is going to be dirty and I'm going to suspect shift quality falls off. Shift quality falling off is a secondary concern, the oil getting extremely dirty is something you can't avoid no matter what oil you run.

The shorter the oil change interval the less benefit synthetic gives in my opinion.

As most have seen, I am a big proponent of the M1 MC oils. But in this case I wouldn't run it, and I never ran it in my older air-cooled ujm's. I would use a 15w40 or 20w50 dino oil. Change it at the interval the stock bike had, or more often if you like to keep fresh oil in it which is almost as important as synthetic or nonsynthetic.

 

[ineptizoid]

I started riding 45 yrs ago and almost never pushed past 2K miles between oil changes on any of my air-cooled motorcycle engines. Always used Castrol GTX 20w50 until the very late 90s when I switched to using Rotella T4 15w40 and Delvac 1300 15w40. If I decided to quit using HDEO for whatever reason, I’d go back to Castrol GTX without hesitation.