Gearbox oil

[JohnBM]

I will be changing the gasket on the gearbox shortly & normally use Castrol oils for engine etc . What do others use , if using Castrol ? There’s a castrol universal 80/90. For manual transmissions . The GMH manual shows straight run mineral oil SAE 90 . I’m probably worrying about nothing . Cheers John .

[Errol62]

Just using gulf western 80/90 with 20% Morey’s heavy duty oil stabiliser.


Sent from my iPad using Tapatalk

[JohnBM]

Thanks Errol , I see you use Moreys as well , good to see . It seems that using 80/90 oil is the go & whatever brand is a personal choice . Thanks for reply .cheers John.

[Errol62]

👍👍


Sent from my iPad using Tapatalk

[Trevor_B]

Hi John,
If you want a direct replacement for the GMH Oil then use Penrite Transoil 90: https://www.penriteoil.com.au/products/transoil-sae-90 It is a straight SAE90 Mineral Oil.

It is important not to use multi grade or friction modified oils in grey gearboxes as they can impact the function of the syncromesh engagement.

Cheers,
Trevor_B