John Deere oil in 14 bolt SMF Z71 Silverado

[CRF450R]

So I have a 98 Z71 Silverado 5.7 gutless high mileage gas pig vortec but it has a 14bolt locking 3:73 rear factory installed diff. At 330 000km in change roughly I changed the all the fluids on the truck engine coolant both diffs and transfercase Ive since switched all my fluids over to all John Deere fluids. I thought my rear diff locker stopped working but decided today to head through some deep snow behind the shop and nope both tires left indications they they were both chewing. This diff always shuttered and clunked and banged but now that II switche to John Deere oil that locker is so quiet and smooth I thought it gave up the goghst. I suggest giving this JD oil a taste

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in you G80 locker

 

[df2x4]

I'm sorry but this is a terrible idea. If you have a G80 you should be running heavy GL5 80W-90 with no friction modifier or additive. JD Hygard is closer to regular motor oil than gear oil in viscosity and god knows what else is in it. G80s do not want anything but straight gear oil.

 

[df2x4]

Side note, the behavior you're describing before switching to Hygard sounds like a textbook example of someone putting friction modifier in when they weren't supposed to. I'm betting the performance increase you're noticing is simply from cleaning all the residual additive out of the locker.

If I were you, I'd drain the diffs and fill them both with the correct oil.

 

[someotherguy]

Beat me to it, on both counts.

Richard

 

[94HDbigblock]

I work at john deere hy-gard is basically hydraulic oil with detergent. I say the detergent in the oil cleaned out the locker and it working correctly now. I would drain the oil out and go back to 80-90w