PYB @ the family farm. grampa used 10w30 as long as i remember. the last few years its been 5w30.
Our fleet includes farmall I-H tractors, 300, H, M, super H, super M, 560 diesel.
all gassers get pyb. the diesel is a shed queen (10hrs/5yrs). I have not a clue what the diesel has in it. it been a idle piece since grampa died.
the 560 will get 15w40 pennzoil long life, if i can't get pennzoil ll in 30/40 wieght.