I've never had a blower failure ('cept for when some dckhEd didn't tighten the drain plug and it ran dry)
Don't ask who the dckhEd was.... yes, I really clean up pet shit for a living Dad..
I hear about blower failures and wonder why..cause they're by far the most durable component on a TM..and will take quite a bit of abuse
anyway, I've used nothing but 80wt gear oil in the blowers
my last TM had over 12,000 hours on the original blower (Roots 45)
never did a thing to it 'cept change the GEAR oil once in awhile and gave the bearing a shot of grease every now and then
i use synthetic gear oil now and that's the only thing I do different in 21 years
a TM is ALWAYS above 32 degrees
and runs in an ambient temp environment well above 100 degrees
30wt non detergent in the pump
..l.T.A.