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MG Midget and Sprite Technical - Axle. Which oil?

I've just fitted new thrusts to my 4.2 diff.
Workshop manual states EP90 as the correct oil. I bought some today, but after purchase I noticed it is to GL5 spec.
The new Sun gear thrusts are fibre, but the Planet gear thrusts are what I presume is Bronze and I am concerned that GL5 will attack them. So before I install the oil, is it OK to do so, or should look for something else. If so, what?
Bernie Higginson

I've used Comma EP90 GL5 in my diff for around 10 years with no apparent ill-effects.
David Smith

Thanks David. I just didn't want to have to pull the diff again after a few hundred miles.
Bernie Higginson

I thought you were supposed to use GL4, but if GL5 works so be it.

Comma brand EP 80w/90 GL4 is a tenner in Halfords for 1 litre. I know as I bought some just last week! The website shows a cheaper own brand oil for 8.49, but I couldn't find that in my local shop of eternal disappointment.

Like for like brands, GL4 appears to be a bit cheaper.

Malcolm Le Chevalier

Thanks Malc. "My local shop of eternal disappointment". LOL. That's the same opinion of Halfords as I have. They never seem to have exactly what you want, and if they do, next time you go in, it's been discontinued. ie. Castrol Syntrans gearbox oil for my Ford 'box. I had to get some off Ebay.

If you think the 80/90 is OK, I'll get some this aft.
Bernie Higginson

Shop of eternal dissapointment! Describes it well. To be fair, I think it has moved with the times and although once it was a DIY car maintenance emporium, far fewer folk these days get as far as opening the bonnet on their cars. Hafords have followed suit and their focus is more on non specialist bikes and stuff like sat navs. and car cleaning products.

I do find the search engine on their website frustrating though. Type in a specific item that you want and it comes up with a completely unrelated and random list of things they think you should buy!

Car parts and websites!!! Eurocarparts or what ever they call themselves really p*sses me off. You can't find anything without putting in a reg no which it then will say it stocks "nothing"! No oil, no brake fluid, nowt!
Graeme Williams

Graeme, that's not correct.
At the top of the page there's a search box, if you put in what you want eg EP90 it will show you all the brands and sizes available.
For general stuff you can also go in via the Accessories option in the menu line.
David Smith

For those that travel abroad savings can be made by visiting French supermarkets.
I get my 80/90 EP Castrol - 2 litres for about 10.
Worth, also, checking out the anti-freeze.

It is not just Euro car parts that can irritate with a demand for a registration number Graeme. I did find them very helpful when searching for a release bearing to make up my Spridget roller release bearing. The item chosen now has to be 'special order' but is usually in store next day. After the first dozen they did ask what I was doing with them.

Alan Anstead

In fairness Halford's have done okay for me with oils, filters, axle stands and so on. Delivered free to the door if you buy enough in one go. Anything from 20 up last time I bought oil. We're a bit remote here so the free delivery was very nice indeed.
Had no problem getting GL4 gear oil from them.

Just my 2 cents.

I remember our old friend Nigel delving into axle oil and using a synthetic type which he swore by.

He said it reduced the noise from his diff noticeably...
Andy Phillips (frankenfrog)

fwiw I added some synthetic oil additive (Teflon??) to the diff(3.7 ratio??) and gearbox on the 1500 with new standard 80/90 gear oil with excellent results, everything is quieter and the gearbox changes smoothly.
R W Bowers


Comma still sell EP90 oil to GL4:

As do Miller Oils:

Like Andy I remember BBS threads on the topic, so worth a search too.


M Wood

In one way the G4 / GL5 rating is irrelevant for differentials. GL5 has more of the additives put in for modern synchros that would damage the yellow metal synchro rings in an older gearbox. But GL5 has better performance for extreme duty gears than GL4, and is the better choice for a differential where there aren't any yellow metal synchros. Just don't put it in your gearbox!

Only last month once again I changed the diff oil and it immediately quietened the diff. I last changed it two years ago, with the same oil.

I read some years ago that a contributor changed his diff oil every year and found that that kept the (noticeable?) noise away. He used a different oil to me.

The oil I use is - Mobil Mobilube 1 SHC 75W-90 (fully synthetic).

Yes, a blast from the past.
Nigel Atkins

It's great to see you back Nigel!

I confess I use the same in 'box and diff. EP85 GL4 from Halfords. I have no undue worrying noises from either though last time (only time) I changed it I noticed the downshift 4th to 3rd got a bit slicker.

Thanks Greybeard.

My change of diff oil kept things quiet for less than two years so perhaps the annual change suggested by the other contributor (sorry but I can't remember who) might be needed. Even the Mobilube I use isn't expensive so it's good value over one or two years compared to a whine on a long distance journey in my midget without soundproofing and the hood up, especially if it's raining too. I also like to see how clean or contaminated the emptied oil is.

As they say, other oils are also available, you pay your pennies and make your choice, each to their own, etc..

Nigel Atkins

This thread was discussed between 04/08/2016 and 08/08/2016

MG Midget and Sprite Technical index

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