I went in to change my gearbox and diff oil on my my99 imp turbo. the manual states it need gl5 spec oil for both, but it seemed that only gl4 spec oil was available. finally found gl5 oil but is seemed like it was for heavy machinery use. it said on the bottle that it was for "heavy duty axles and non-synchronous transmissions" (shell) is this the oil that i need or is gl4 ok?

zak

 

Your handbook will tell you that if GL5 is not available then GL4 is acceptable. A favorite on here is Castrol Syntrax (now labelled Driveline) which is GL5 Cheapest way to buy is straight from Castrol www.castrolclassicoils.co.uk or you could go to Halfords - but pay more!
JohnD