Last fall I replaced the gear oil in my 91 Toyota Previa 5MT AWD. The manual calls for "multipurpose gear oil GL-4 or GL-5 75W-90" for both the manual gearbox and the transfer. I had a hard time finding many 75W-90 options locally, and none were GL-4. I ending up going with Coastal dino 75W-90 GL-5 from Autozone. I hate this oil in the MT, the trans feels a lot more notchy than before, and I'm replacing it this weekend with Red Line MT-90 which is a true synthetic GL-4 75W-90 and has been highly recommended by several people.
My question is, what should I use in the transfer? In the past, I tried Supertech synthetic 75W90 GL-5, but it leaked, so I switched back to the dino and it stopped. Never had a problem with the transfer, but would like to use better (synthetic) oil in there. I'm seeing a few options on the Red Line site for 75W-90:
(1) 75W-90 GL-5 gear oil (57904)- Says this is OK for most LSDs...might be too slippery for a transfer case or open diffs?
(2) 75W-85 GL-5 gear oil (50104) - Red Line says "Popular in many Toyota light truck differentials and transfer cases"
(3) The same MT-90 75W90 GL-4 Gear Oil (50304) I'm planning to use in the 5MT, or
(4) 75W90 NS ("non-slip") GL-5 Gear Oil (58304), which says "Contains extreme pressure additives like our 75W90 GL-5 oil, but lacks friction modifiers to balance slipperiness".
While I'm at it, which of these would be best in the Diffs, which call for hypoid gear oil GL-5 80W-90 (although I've spoken with many different Toyota dealers who just use dino 75W-90 in everything). I don't see any 80W-90 specifically made by Red Line, but their application guide for this vehicle says the following:
MT-90 75W90 GL-4 Gear Oil
•For use in manual transmission
75W90 GL-5 Gear Oil
•For use in front differential with AWD
•For use in rear differential
But they don't mention the transfer case...
Thanks for any advice.
My question is, what should I use in the transfer? In the past, I tried Supertech synthetic 75W90 GL-5, but it leaked, so I switched back to the dino and it stopped. Never had a problem with the transfer, but would like to use better (synthetic) oil in there. I'm seeing a few options on the Red Line site for 75W-90:
(1) 75W-90 GL-5 gear oil (57904)- Says this is OK for most LSDs...might be too slippery for a transfer case or open diffs?
(2) 75W-85 GL-5 gear oil (50104) - Red Line says "Popular in many Toyota light truck differentials and transfer cases"
(3) The same MT-90 75W90 GL-4 Gear Oil (50304) I'm planning to use in the 5MT, or
(4) 75W90 NS ("non-slip") GL-5 Gear Oil (58304), which says "Contains extreme pressure additives like our 75W90 GL-5 oil, but lacks friction modifiers to balance slipperiness".
While I'm at it, which of these would be best in the Diffs, which call for hypoid gear oil GL-5 80W-90 (although I've spoken with many different Toyota dealers who just use dino 75W-90 in everything). I don't see any 80W-90 specifically made by Red Line, but their application guide for this vehicle says the following:
MT-90 75W90 GL-4 Gear Oil
•For use in manual transmission
75W90 GL-5 Gear Oil
•For use in front differential with AWD
•For use in rear differential
But they don't mention the transfer case...
Thanks for any advice.