Morris Minor Owners Club

les wrote:I wouldn't want ep90 in my gearbox but experiment on yours and let us know what happens.

Out of curiosity, what do you think could go wrong?

To be honest I've no Idea, it's in the diff, which also has gearwheels but maybe it would interfere with the gear selecting. I'm waiting to hear if whyperion tried it!

EP 90 is a bit 'thick' for the gearbox , so would affect selection especially when cold - but the main problem seems to be the possible erosion of bronze parts - selector forks/bushes etc.

Be nice to know a definitive answer regarding destroying certain metals. Can't imagine selector forks etc melting overnight. Perhaps I'll drop one in some ep90!

Nearly all manual gearboxes rely on oil flow 'from the gears' around the casing and to the bearings.
The viscosity difference between SAE30 and EP90 should be enough reason not to try it as it won't lubricate properly.

as for how much lifetime you loose - I've no good data... but I did run EP90 in a Minor box many decades ago, and the box died. I didn't do it again!

Hi
Glad to know other Minor owners have tried what I have been thinking, but you are all wiser than me as I fail to see how a different oil could affect the metal parts other than if the different oil does not flow to the parts and they run dry.
Rayofleamington's last post makes sense to me so I think I will leave the oil in the gearbox alone and thanks to BMCecosse , I genuinely had forgot about the final drive!!
David

I do not see much difference in the internals when say comparing the Ford gearbox against the Minor gearbox. The Ford gearbox uses EP90 oil as do several other marques.
I always used a straight 30 grade oil in the Minor gear box when it was fitted to my Minor previous to my fitting the Ford gearbox.
During my apprenticeship at the BMC main agents I was told that using EP 90 in the Minor gearbox would make engaging the synchro cones with the synchroniser difficult as the EP 90 would not completely clear from the faces of the synchro cone and the synchroniser leading to failure of the cones/synchroniser and ultimately leading to the inability to change gear.
What is the difference between the Minor synchro cones/synchroniser and the Ford ones? I do not know as I have rebuilt both makes of gearboxes on more than one occasion and there are no outstanding differences to be seen.

I have a Marina box fitted to mine and it uses EP 90. However, it doesn't always engage 1st gear easily (It doesn't crunch, just wont select, even with a double de-clutch) and I was going to try Automatic transmission fluid.

This is what I have heard is done (by some folk) when a similar problem occurs to the old Toyota 5-speed boxes.

My TR7 (LT77) box uses EP 90 and is 'difficult' on 2nd gear till it warms up. The TR7 forum has long discussions about changing to MTF oil (not ATF) for an improvement - but I will just stick with the EP90 - mainly because I have a few bottles 'in stock' !

FWIW, our 05 Dodge truck w/a Getrag manual transmission uses ATF for a lubricant. Previous to that we had a "93 Ford truck w/a Mazda manual transmission and it also used ATF.

Regarding EP90 oil and it's eating brass and/or bronze, don't believe it. I heard that years ago and did an experiment, put some EP90 in a jar along with a piece of brass and a piece of bronze and after a couple of years there wasn't even a discolouration of the pieces, never mind any "eating away".

I fail to see how a different oil could affect the metal parts other than if the different oil does not flow to the parts and they run dry.

I have seen a few write-ups explaining that EP90 will damage bronze bushes - I'm sure it is theoretically possible as EP has a lot of weird/wonderful additives for the high pressure stability, but the anarchist in me wonders where all the bronze goes to!

A clever man does not necessarily know the answer to a question but he knows where to go to find the answer.

It apparently is seen running out with the old oil as a 'golden' colour. Not done/seen it myself - so just hearsay...