Cheapest place to buy Gearbox oil...NOT FOR A SUBARU
 

I need to change the gearbox/diff oil in my Land Rover.
I need about 7litres in total of plain no-frills standard 90w oil

Odd, but I can't find anywhere on the net that sells it (except synthetics @ £10+ per litre...owch).

A few pointers/prices would be handy before I go wandering off to the local motor factors. :)

Seeing I already can get a well known synth for £7.80 a litre, I want something MUCH cheaper!

TIA