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Transfer/Diff Gear oils

ModelMakerMan

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Joined
Jun 25, 2011
Messages
599
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england
Its time to replace all the oils on my KZJ70. The service manual says I need SAE75w-90 GL5 for the gearbox and SAE90 Hypoid GL5 for the transfer and diffs above -18*C and SAE80w-90 Hypoid GL5 below -18*C.

A couple of questions:

Is it worth the extra money to put fully synthetic oil in the gearbox and transfer? (I change the diff oil too often to be able to afford synthetic for those!)

Opie Oils has the transfer and diff oils as 80w-90 GL5 but the Toyota service manual only specs that for below -18*c and its very rare it gets that cold here in the UK! Im pretty sure the oil Ive been using in the diffs is 80w-90. The selection of SAE90 hypoid oils is pretty basic and limited whereas there is a far better selection of 80w-90 hypoid oils. Am I ok to carry on using 80w-90 oils or should I go for SAE90 instead?

What does everyone use use and where from?

Cheers
Dave
 
Quite a few people use 10w40 engine oil for their gearboxes. If you change it frequently I don't think there would be a problem
 
80w90 and sae90 have the same viscosity when warm and the multigrade oil will perform better in cold conditions. You don't need to use it below -18 to see the benefits in the multigrade oil over the single grade oil.

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Good point Rob, makes sense. I was obviously over thinking it last night. Serves me right for trying work it out when I should have been going to bed!
 
Quite a few people use 10w40 engine oil for their gearboxes. If you change it frequently I don't think there would be a problem

If you need to change it frequently, it's an indication that it is not the right oil. Engine oil is for engines and gear oil is for gears.

Roger
 
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I used the following millers products:

Front Axle, Gear Box, & Transfer Box Millers Oil TRX 75w90 semi synthetic
Rear Axle If LSD Millers Limited Slip 90 or if not available
 
Last edited:
I would only use fully synthetic in the gearbox and put semi in the transfer case and diffs as they are less fussy. The manual gearbox tends to be much smoother if fully synthetic oil is used, well at least on the 80 it is.

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