yet another oil question

[lewdon]

I am sorry if this subject has been worked to death but I have read all the wisdom I can find concerning recommended oil for the Type N (reverse next to first) gearbox on my S2, I have no idea what is in it at the moment but the gearchange is fine. The favourite choice seems to be Comma 75/90 semi synthetic GL4 .
I have contacted Opie oils who say I should use Auto Transmission Fluid in the gearbox. Has anyone used ATF?
As I want to change both the back axle and the gearbox oil this winter I was hoping to find an oil that would be suitable for both the diff and the gearbox so I can buy a five gallon can rather than messing about with litre bottles. Does anyone use the same oil in both?
Any advice will be very gratefully received.

[v8s4me]

Stay away from ATF and use specialist gearbox oil. Wiser V6 heads will be along soon with positive contributions.

[TurboTony]

general wisdom is NOT to use ATF. Mine runs on gear oil and I topped it up with the Comma oil you mentioned. Capacity is small enough not to warrant buying 5 gallons IMHO - you would have lots left over.

[phillpot]

I'd agree with the 75-90w semi (not fully) synthetic, and more importantly, so would a reputable gearbox specialists I spoke with.

Shouldn't the diff be Hypoid / EP 90 ?

[lewdon]

thanks for your help, i'll go with the Comma 75/90 semi synthetic GL4 for the gearbox.
Will this also be ok for the diff? If so I can get 5 gallons which will be enough to fill both the gearbox and the back axle. what do you all use in the differential?

[phillpot]

lewdon said:

Will this also be ok for the diff?

Handbook quotes...API GL5 LS90 Gear Oil

Haynes Sierra manual goes with SAE 90 Hypoid

Haynes Granada/Scorpio (V similar diff) SAE 90EP API GL5 Gear oil

lewdon said:

If so I can get 5 gallons which will be enough to fill both the gearbox and the back axle.

Several times over !!!!

5 litres would be more than enough but I wouldn't be using the same oil in both of them.

[lewdon]

Thanks, I think I will go for the hypoid for the back axle. I had assumed that "API GL5 LS90 Gear Oil" would be virtually the same as "API 75/90 semi synthetic GL4" . not knowing if G4 Vs G5 was significant. Your right 5 gallons would be a bit excessive! wonder why I kept typing that when I meant litres, stupid or what.

[phillpot]

lewdon said:

not knowing if G4 Vs G5 was significant.

Bit of light reading for you........ clicky


It's American, with a lot of reference to old Chevrolet Corvairs, but nevertheless quite straight forward and informative

[lewdon]

Very interesting, and all is now clear. Thank you Phillpot you have an amazing store of information.