Transmission oil

[sandglobe]

Hi, does anyone have any recommendations for modern oil or are they not a negative application?

[RobPearce]

It's not that critical but you need a good quality EP90 GL4 oil. There are some GL5 oils that are OK but make sure it's explicitly marked as yellow-metal compatible because GL5 that is not marked as such my attack bits of the gearbox or diff on our cars.

I normally use Morris oil these days.

[sandglobe]

Quoted from RobPearce-

It's not that critical but you need a good quality EP90 GL4 oil. There are some GL5 oils that are OK but make sure it's explicitly marked as yellow-metal compatible because GL5 that is not marked as such my attack bits of the gearbox or diff on our cars.

I normally use Morris oil these days.

Thanks for the help rob

[Clive]

I still wouldn't use GL5 in a gearbox, even if yellow meta safe.

Having pondered that issue a while ago, I came across a technical article. Even much more modern cars don't likeGL5 oil in boxes, in particular the synchros. Can cause poor gear change as the synchros don't grip the hub correctly. Nissan was one manufacturer who had this issue.

I have used Comma SX75-90 GL4 oil in my ford T9 box. The best rebuilder recommends it, and the spec would work in a triumph. 

However, I have been using comma, and more recently millers, 80/90 GL4 in my triumphs since 1989, covered probably 200k over a number of cars, no issues with the oil. 

If you drive the car really hard, Redline do some quality oils.

[Guppy916]

I use this oil in the GT6 Mk3 box

[sandglobe]

Quoted from cliftyhanger-

I still wouldn't use GL5 in a gearbox, even if yellow meta safe.

Having pondered that issue a while ago, I came across a technical article. Even much more modern cars don't likeGL5 oil in boxes, in particular the synchros. Can cause poor gear change as the synchros don't grip the hub correctly. Nissan was one manufacturer who had this issue.

I have used Comma SX75-90 GL4 oil in my ford T9 box. The best rebuilder recommends it, and the spec would work in a triumph. 

However, I have been using comma, and more recently millers, 80/90 GL4 in my triumphs since 1989, covered probably 200k over a number of cars, no issues with the oil. 

If you drive the car really hard, Redline do some quality oils.

Thanks Clive will avoid gl5 then and look at the redline oils to see if they would be more appropriate

[Scimher]

...I added a tube of 'transmission molyslip' to my last gearbox, yonks ago - as well as adding one in the diff......( The current one was fitted by my pro. pal & he changed the oil - that box is an all-synchro. Spitfire unit - & it was not changed due to any failure of the original ...)

[Bradison]

On 28/10/2020 at 08:00, RobPearce said:

It's not that critical but you need a good quality EP90 GL4 oil. There are some GL5 oils that are OK but make sure it's explicitly marked as yellow-metal compatible because GL5 that is not marked as such my attack bits of the gearbox or diff on our cars.

I normally use Morris oil these days.

This is what I have bought for my gearbox, it comes highly recommended by upstanding members of the Triumph world.

[Spitfire6]

Find a GL5 that is manual synchromesh approved. 
Stop the no GL5 for manual transmission myth.