Synthetic Gear Oil Question

[Kevbo 80]

When I first found this forum you guys did an amazing job teaching me how to flush my trannys and replace the fluid.

 

I have done this process in all of my tractors and have just put cheap Wal-Mart 80W-90 to save money and make sure any leaky seals were replaced before I put in the "good stuff".

 

I have chosen Mobil 1 sythnethic for when I decide to drain out the Wal-Mart and I have two questions:

 

1) Is it better to go with 75W-140 or 75W-90?

 

2) The 75W seems thinner than other gear oils, this is not an issue I imagine?

 

[Jim_M 178]

I would probably use the 75W90. The 75W140 gets pretty thick when it's cold. I tried 75W140 Royal purple in my 654, I was using it for snow removal, it was thick enough when it was cold that it would creep in neutral when you let the clutch out.

[KATO 115]

 75W90 for sure 75w140 is more HEAVY DUTY and not required !!

[Fordiesel69 263]

Being I only operate in the summer I used the 75-140.  But as bullet proof as these are 75-90 would also be fine.

 

They are fairly tough with exception to the HIGH/LOW shift fork.  So don;t jam it in if it won;t go.

[bob393 3]

I'm a 75W90 guy but I'm not a good example as I blew out the needle bearings on my C-120 8 speed.

Edited May 20, 2013 by bob393

[Kevbo 80]

How did that happen? Just naturally?

[Fordiesel69 263]

The other thing to consider, is moisture and metal will accumulate in the fluid.  My personal perference is to change more often rather then using expensive fluid.  The only time I think synthetic fluid would be better is if you operate 8 hrs solid and it gets hot.  Which I don;t beleive it would get that hot.  Or conversly if you operate in the winter, it will flow better.

[bob393 3]

How did that happen? Just naturally?

 

Unfortunately I think that's why because I don't abuse it.

I feel I take pretty good care of it with regular greasing, oil changes, and adjustments.

[MalMac 1,331]

We are talking a small garden tractor transmission, not a transmission out of a big hi-way truck pulling a 53ft trailer. The pressures and heat generated by a big truck compared to that of a 8-speed Uni-Drive is totally different thus the need for the real heavy weight is not needed. If it is needed I am not sure what your trying to do with the Uni-Drive is safe for the operator or the tractor. This is just my opinion of course and I think the 75w-90 is plenty heavy enough.

[pfrederi 17,887]

Consider that for several years WH specified 40w motor oil for the transmission.  MY L-107 is working just fine after 46 yrs of consistent use running 40w in the rearend..

[meadowfield 2,595]

ditto that - my C-101 has run on 10W40 motor oil for the last 3 years. I figured if it's good enough for a modern vehicle with shared engine and gearbox running at 80 deg C it's good enough...