Morris Minor Owners Club

hi folks i am thinking about changing the oil in the diff.i have had the car 3 years and i dont think,this has been done whilst i have had the car .is it just a case of undoing the drain plug let it drain out.should i flush some petrol through it to get rid of crud or not.then you refill with ep 90,is there anything else i need to know thanks dale.

Did mine few weeks ago, sprayed the drain & fill plug day before with pebetrant which may have helped.
I wouldnt flush with petrol - any residue could break down the oil to a detrimental point.
If its really yukky then run it for a few months and change it again - i.e. using this full as a flush, thats what i'm doing even though it wasnt as bad as expected.
Did the gearbox at the same time and greased up the UJ's on teh prop, quietened it down a lot !

Yes Dale, as Orkney says, just drain and refill EP90. Don't flush it. Back axle and gearbox oil change should be every 6000 miles. If you do do the gearbox, 20/50 oil (as engine) goes in it.

thanks dave ,orkney i have had a new gearbox fitted on tuesday so that will be ok.i will change the diff oil and change it after 1000 miles i recon it will full of crud.

Dale i know others will no doubt disagree so this is only my opinion for what its worth but you migth want to consider one of the proprietory gear box treatments if your running a new recon.
Can be as much as £30 some of them but what a differnce they make - not worth it i guess if your changing oil every 6k miles (i didnt know it was such a small distance) but there are some lesser add in treatments for about a fiver which are quite good too.

I always stick a squirt of wynns in mine everytime I change the oil, just a little bit mind. I gather that 'Slick 50' is ptfe based, and it coats the gears, they reckon that its benefits stay even after you change the oil. But I guess the new oils are better in their formulation than the old type anyway..?

the big advantage of any of the dear treatments is that in theory if you holed your gearbox & lost the oil you can go a lot further if youve treated it than if not.
it doesnt make a lot of sense in so much as i think have been told on here that the box needs the viscocity to function correctly for the syncros? and a lot of the treatments are very sticky.
Just seem to run smoother with it though - same with the engine.

ptfe based, and it coats the gears

And the synchro cones, so they won't work properly! I would use a good quality 20w/50 engine on its own.

And the synchro cones

I did wonder about that, and the adverse affect on the cone spin. Reckon you are right Richard, best stick with what is specified.

Back axle and gearbox oil change should be every 6000 miles.

Later BMC Manual information for improved oils is 12,000 miles for diff and gearbox oil. No harm in changing very 6,000 miles, but a waste of money and resources with new oil technology.

For reduced drag in the gearbox - stick to 10W40 oil, and my view is no additive because the syncro barely works as it is!

Didn't realise it should be changed every 12000 miles. I should add this to my list of "things I should have done and will come back to haunt me".

They do, though run better with oil in the diff as I found out last week (Mine supped 2 pints as I scratched my head wondering why it's been whining so much).
Andrew

What do you mean the syncro barely works?

Mine does! Smooth gearchanges all the time (apart from the non-syncro 1st and reverse of course)

hi folks i have done the diff oil,it was easier than i thaught.i drained it out then ran some new ep90 through it with the drain plug still out to hope fully get rid of any crud.it was well dirty,then replaced the drain plug and refilled.i think i was worried that the drain plug would not undo but it was quite loose,thanks for all your advice dale.