Gearbox oil specification

[Tyre_Tread]

In the process of changing the engine on one of my cars I managed to lose about half to one litre of gearbox oil on the floor so it needs topping up.

The handbook recommends GL-3 spec oil. I have some GL-5 spec so is it OK to top up with this?

Is gearbox oil like brake fluid DOT spec i.e backwards compatible?

[V10Mike]

No, you should not put GL5 oil in a gearbox which specifies GL3 or GL4 oil -GL5 has a higher EP performance and may prevent the synchromesh working properly.

[Tyre_Tread]

Thanks Mike.

In between my posting and yours I went along to my local factors as I needed other stuff.

Want to take a guess what they told me?

Want to take a guess what I've already done.

Will it do any harm?