Same oil for manual transmission and differential?

[igeak691]

I've got a 2003 z4 3.0i. I searched around and seems like royal purple is a good choice for transmission fluid and it also seems like differential fluid is the same. Am I looking at the right thing? Royal Purple Max-Gear 75W90 is what I'm planning to buy. I read 2 quarts needed for the transmission. Anyone know how much for the differential? And any recommendations for other brands I should also look into?

 

[igeak691]

Can someone explain the difference between the Royal Purple Max-Gear 75W90 which I think is for the differential, and Royal Purple 01512 Synchromax High Performance Synthetic Manual Transmission Fluid which I believe is for manual transmission? Are they designed differently? Here are links to their amazon product pages:

75w90
http://www.amazon.com/dp/B0007QGT34/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=BVMD19BPOCYE&coliid=I3JUU1C42ZOYEM&psc=1

MTF
http://www.amazon.com/dp/B001DKTG0G/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=BVMD19BPOCYE&coliid=I1C3W3BYK4ZM3S&psc=1

 

[paulgs1000]

He's just mentioned he's on holiday Jonny. . . .

 

[Dewi]

Gearbox oil - BMW spec: http://www.opieoils.co.uk/p-69413-castrol-syntrans-b-75w-full-synthetic-gear-oil-for-bmw-manual-gearboxes.aspx

Diff oil : http://www.opieoils.co.uk/p-737-castrol-syntrax-longlife-75w-90-formerly-saf-xo-75w-90.aspx

This is what's in my car and it's fine

 

[igeak691]

So would it be a bad to put the 75w90 oil into the manual transmission?

 

[Dewi]

Just use whatever BMW or Castrol recommend for the gearbox - i.e an API GL-4 gear oil.

http://oilselector.castrol.com/c/uk/eng/search

 

[igeak691]

Gotcha. Gonna go with Royal Purple Synchromax for the tranny as I read many good reviews and Mobil 1 Synthetic 75w90 for the diff as that has many good reviews as well. How much to fill the tranny and how much to fill the diff?