gearbox oil

[leonard]

hi all,i want to change gearbox oil is 80/90 grade ok,shop said 75 grade dos this matter and why. thanks all

[California Dreamin]

Look for the grade GL4 80w-90 (this is an older standard and not so easy to get hold of now)
or
Recommended by many including myself
Semi synthetic 75w-90 which will almost definately say GL5 but for reasons of formula...you must make sure you buy a product that says GL4 as well (will say something like GL4/GL5) in other words...has been tested and meets the requirements of both standards.

The short explaination to this is GL5 products have additional (more) of one particular additive that protects against the sheer characteristics of Hypoid gears.
Note I said MORE, as GL4 products also have these additives but around half as much.
It is this additive that is said (in certain high temperature conditions) to damage yellow metal components in the gearbox like syncro rings etc.
However, the products that say GL4/GL5 are said to be formulated differently to take into account these issues.

Martin

[leonard]

thanks a lot Martin great help len

[Cyrus]

GSF part number 980AA0660
Carplam gearbox oil, 4.55L so correct amount too.

[Sh!tbucket]

I used a straight SAE80 GL4 ( I think it was carlube of carplan), that was 4.5L too.

Cost me about £15 from a local motorist store (Godfrey Autoparts).