Hey Scotty, I own a Lexus NX 300 F Sport...The front transfer case and rear differential calls for 75w85 GL-5 gear oil. This gear oil is a hard to find item, the dealer wants $30.00 US a liter. Can I use a different brand other than Toyota’s?Mobil 1 makes 75w90...Can this gear oil be used as a replacement? Thanks, Scotty. TaLonnie D
75w85 GL-5 gear oil is so called "light weight gear oil”. It’s viscosity at 100C is 12 CST vs 14.6 and at 40C is 68 CST vs 103 vis-a-vis 75w90 GL-5. It also has a lower pour point: -45C vs 39C. Plus, there is a claim that 75w85 contains "bit more" friction modifiers for suitability with clutch-type limited slip differentials. Bit more, … meaning not much of an discernible, practical difference between the two.
Above said, I would just get 75w85 GL-5 as spec’d by Toyota and be done with it! Mind you, Toyota specs this simply for less gear drag, … but that also will not make much of a difference to your fuel economy. fwiw.
F.S.
This is quite an interesting question.
Personally I’d stick to the OEM fluid, I’d just try to find a store that sells it for cheaper.
on my cars I’ve attempted to put in other brands fluids into gearboxes and it never has ended well.
I tried to put in oil that states that it “does no harm” into my Volvo’s gearbox (MPS6) and with that fluid the gearbox has a whine. I replaced it almost immediately with the OEM (it’s like $25 a litter) and the whining went away.
I’d not risk a Lexus differential to save a hundred or so dollars…
use any oil that meets the spec
So, If I was to break down which a Toyota can do! The only gear oil available is 75w90 Mobil1, Valvoline, Amsoil, Redline. Stuck in the middle of nowhere...Toyota/Lexus no where to be found...I would tell the repair guy: “Use Toyota gear oil only!” Or If I need to top off: “Only use Toyota gear oil!” They would laugh, like I would and say...”It’s a freakin Toyota! Life does not work that way! I’m not trying to save hundreds of dollars...I bought a Lexus because Mercedes are ridiculous expensive! Yet your suggesting not to worry (Toyota/ Lexus) is not far behind! I was looking for Scotty 50+ years advice on this one! Toyota gear oil is the only fluid that crazy over priced... The rest of their fluids are reasonable...Which seems very suspicious...The manual reads to use Toyota 75w85 gear oil or equivalent! Since Scotty is 50+ years auto mechanic I was looking for his input on the “Equivalent!”
To be fair, you also are NOT replacing these fluids that often unlike engine oil. If you were doing this every 5,000 miles then I see your point. But as long as it meets Toyota spec, it should be fine. And yes if you were stuck in middle of nowhere, then you can only do so much. When it comes to the automatic transmission, I would only use OEM to be safe, and even then you are changing every 40,000-60,000 miles so easier to stomach the cost.