My BMW motorcycle requires 70W80 GL5 gear oil in its final rear drive. It looks like BMW changed the spec from 75W90 to 70W80 a few years ago. The 70W80 GL5 is not easy to find. You can buy it at your local BMW dealer for $60 for a 1/2 quart. The bottle looks like a Fuchs product. The other alternative is the Mopar 70W80 for $19 for a quart. I bought the Mopar stuff.
70W80 gear oil
- Thread starter Finklejag
- Start date
My Escalade uses 75W/80 in the rear differential as well. I spoke to HPL, and was informed it’s an efficiency CAFE thing, and it would be perfectly acceptable to use HPL 75W/90, so I did- replaced the front & rear diff fluids with HPL 75W/90 (the front diffential specified 75W/90- the rear 75W/80). It’s working fine with 75W/90 all around.
Or there's enough anecdotal that the Amsoil Manual Synchromesh allows for faster 4hi engagement that I'm inclined to believe it. That's what I recently put in a '15 Tundra.
75W85 might have been easier to find as it's becoming more common.
BMW have come a long way with the motorcycle final drive spec. It started as straight 90W back in the 70's with 80W acceptable in winter. Then 80W90 was permissible year round. I use 75W90 in my 1979 model but next time may use 75W85 which my car takes. I wouldn't describe the difference between these grades as minor when the oil is cold. I can tell the difference with ease just by spinning the rear wheel by hand with the bike on the center stand. At 0 deg C a synthetic 75W90 is around 750 cSt compared to the 80W90 at 2500 cSt.
I think you did right getting the correct grade.
BMW have come a long way with the motorcycle final drive spec. It started as straight 90W back in the 70's with 80W acceptable in winter. Then 80W90 was permissible year round. I use 75W90 in my 1979 model but next time may use 75W85 which my car takes. I wouldn't describe the difference between these grades as minor when the oil is cold. I can tell the difference with ease just by spinning the rear wheel by hand with the bike on the center stand. At 0 deg C a synthetic 75W90 is around 750 cSt compared to the 80W90 at 2500 cSt.
I think you did right getting the correct grade.
if your happy
Because the viscosity of gearbox and engine oils are measured on
different scales, an SAE 80 gear oil is roughly equivalent in
viscosity to an SAE 20 grade engine oil... and SAE 90 gear oil is
roughly equivalent to SAE 40 grade engine oil...
different scales, an SAE 80 gear oil is roughly equivalent in
viscosity to an SAE 20 grade engine oil... and SAE 90 gear oil is
roughly equivalent to SAE 40 grade engine oil...
They likely went to a thinner oil to get a slight bump in fuel economy. There is no issues using 75w90.
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