i like a 15w40 C/S rated oil for my engines.. some people run 10w30 in the gassers. red tigers usually have preety good oil pressure even when old and abused. your call.
for the hyds, trans, diffy sumps. a utf Meeting M2C134 spec. most house brands will meet this.
You COULD go with a 80w90 gear oil inthe trans and diffy, and utf inthe hyds.. but if the pto inter sump seal is leaky as many are.. you will get mic from hyds to rear... plus many find it easier to buy 1 pail of oil, and not piece it together with pails and jugs..e tc.
that plain jane utf will be fine in the loader seperate sump hyds too.