Oil debate goes on, on, on and on.
HDEO oil = Heavy Duty Engine Oil.
Like all other oils, you have good ones, bad ones, and great ones. Most of these HDEO oils are rated for gasoline engines. (Have never read a bottle that said desiel specific oil).
These oils are rated for use in you cummins, allison, detroit trannys (automatics).
These clutch plates require the same kind of lubrication as that of a motorcycle. These trannys are seriously abused behind 500+ horse turbocharged diesel engines, continuously slammed from forward to reverse.
I have asked this same question before and will ask again "Does any one have any proof of a clutch failure due to the use of a non motorcycle specific oil"?