Diif oil

[Gavin3659]

Im wanting to top up my diff oil and i found this oil in my workshop. Are either of these suitable or am i better buying something different?[frame][/frame]

[amgrave]

There was talk a while back about GL-5 type affected some metals in the moggy axle so if anyone can confirm this or your not sure might be best to use GL-4.

[liammonty]

GL5 definitely affects phosphor-bronze, so shouldn't be used in the gearboxes of older cars that contain such components (such as my old T2 VW or Citroen DS!) but the Minor gearbox (post MM at least) takes engine oil, so that isn't a problem.

I'm not convinced that there is any phosphor-bronze type metally stuff in the diff, in which case the oil you've got will be absolutely fine - however, I'm not 100% certain, so stand to be corrected! Whatever the case, GL4 would be 'safe' to use.

EDIT

I'm wrong - there is bronze in the diff - see below! Posted by IslipMinor:

There are bronze thrust washers behind the planet gears in the diff itself - these have been believed/known to be 'eaten' by EP additives.

From a previous posting EP90 GL4 was the recommend type for the rear axle, I think? Lots of comments if you Google GL5 about eating yellow metals and you should use GL4.

The manufacturer’s specification for this car calls for a GL5

This is not true and worries be greatly as neither Comma nor the API rating existed when the Minor was first made, or probably not during its whole production life!

Interestingly Mobil are very clear in saying that any axle with yellow metal should only use GL4 - this is their website statement:

'There are transmission applications that recommend API GL-4 type products where we would not recommend using an API GL-5 fluid because transmissions typically have components made from “yellow” metals. However real axles where GL-4 fluids are recommended do not have “yellow” metal components. As a result, the application of an API GL-5 fluid is acceptable.'

The typo is theirs, not mine (real)!

I would only use a GL4 EP90 oil in the Minor rear axle, or more likely these days an EP80/90, but still to GL4 standard, not GL5.

[Gavin3659]

Thanks for your replies.