sourcing Eaton Transmission fluid or alternative

[Goofball1205]

I have a 1979 International truck that I use to spray water on my private motocross track. It gets used a handful of times a year for 5 hours or so. I have no idea when the last time the transmission fluid was changed so I'd like to give it some fresh fluid and see if it improves shifting or at least prolongs the transmission. It call for Eaton PS-386 spec which replaced Eaton ps-164rev7. Im trying to source 8qts but cannot find anything less then a 5 gallon pail for over $200 online. Anyone know of a transmission fluid that would work in this situation that could be locally sourced in gallon containers? I have no use for extra transmission fluid as this is the only truck I own. The only one Ive found in gallon containers is Mobil Delvac transmission 50wt which meets PS-164rev7 which I can't see being a problem if I could get my hands on some.

 

[nascarnation]

Agree a half million mile rated heavy duty synthetic lube is total overkill for what you're doing.
How about a 15W40 engine oil? I think that's what the Army uses in their manuals.
You're certainly not going to wear this out any time soon.

 

[Goofball1205]

I got it figured out. Posting for someone they may find this searching. I found a copy of the service manual from eaton for my RT-6613 and it calls for API GL-1 90 weight gear oil or heavy duty engine oil Mil-L-2104B, API C,D,SF, or CD in 40 or 50 weight. all these are for above 10*F.