[AT] Tractor Fluid (OT, only maybe)

[Greg Hass]

To get a little off track, I hate it when they change oils. Two years 
ago I bought a new JD Zero turn mower. The book said to use 20W-50 in 
the hydrostat; it came with the usual warning of (do not substitute), 
and of course the big one; DO NOT MIX OILS. Even though the mower was 
new, I like to have the basics on hand and as they didn't have the oil 
in stock I had them order a quart (according to the book you never 
change the trans oil, just add if needed). A couple of weeks later I 
stopped at the dealer to pick up the oil. The parts guy disappeared into 
the back for a while and then returned with an update sheet which stated 
that the 20W-50 oil is not available. It further said that engineering 
had approved 15W-40 Plus II for use in the transmission. WAIT A MINUTE: 
what happened to the DO NOT MIX OILS? I guess you need not read or 
listen to the book but just throw in some oil.
To get back to old tractors, I have run into the same problem with my 49 
Cub. The book said, and I have used since owning it(about 12 years) to 
use 20W oil in the engine. Growing up and into my 20's, at various times 
we used, IH, a super c, a 350 utility, and a 504 Farmall. None were 
abused, but all were used hard. 20W oil was used in all of them year 
around and we never had a problem with any of them. A couple of years 
ago I tried to get some oil for the cub only to find that 20W is no 
longer made; I checked 5 places and the Penzoil dealer even called his 
distributor. The cub is the only tractor I have that now uses this oil 
and up until now I had enough for my needs but my supply is gone. What 
should I do now? 30W seems a bit heavy as most work is light and takes 
under an hour and it doesn't get all that hot, however I do have a disk 
and field cultivator for it and then it does really work. I could use 
10W-30 but when it gets hot the oil pressure is almost on red; although 
it uses almost no oil. I almost never run it in freezing weather. I am 
leaning towards IH 30W low ash oil as I already keep it on hand for my 
715 gas combine, but I just don't know.
It's sort of like was has come up on the list before a couple of times. 
What oil is used in a Cub transmission? Some people said 90W; others 
said hy-tran. I couldn't figure the different answers until I found out 
that both answers are correct. Early Cubs use 90W, later models use 
hy-tran even though its the same transmission. I liked the common sense 
(which is sadly lacking today) answer one member gave as to which oil to 
use; if you have good seals, use hy-tran; if the seals leak some, use 90W.
          Greg Hass