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MG MGB Technical - OD Transmission Oil dillema

Have the LH Type overdrive. Underneath doing some maintanence and noticed quite a bit of oil leaking off the rear body crossmember, just under the OD unit. Cleaned and tightened everything up and will be investigating the leak problem is I need to top up the gearbox and am not sure what to use? I have read ALOT of the Oil recommendations in the archives but? I drained a little of the oil and it seems a bit thicker, cleaner and more slick than what I would expect used 20/50 to look like. It seems to have the very faintest of gear oil smell, but can't be sure. Can I top up with engine oil? or possibly go with EP 80 hypoid? will either one cause problems if mixed? I am just worried, I don't want to screw anythin up as my OD works PERFECTLY. Thanks
Mike
MK Mike

Hello Mike,

Owners manual recommends 20W50 like engine oil. But I also owned 3 volvos 240 series with same OD than B, and according to Volvo manual: ATF is their suggestion.

Avoid any synthetic oil for shure...


Cheers,

J. G.
Jean Guy Catford

Stick to 20w/50 and DON'T use any additives! If in doubt drain both O/D and box and re-fill.
Allan

JG, I have seen that also. What's in mine is definatly not ATF, and I know not to use Synthetic. I guess if I top up with the 20/50 I should be safe???? Gusee if we see any diffeerence in the OD performance it will be immediatly drained and refilled.
Mike
MK Mike

J.G.: Yes Volvo 240's use ATF in their 4-speed and O/D transmissions. When I worked in the Parts Division Of V.N.A. I questioned Product Quality on this item. I was assured ATF is correect.

Curious to know about NOT using synthetic in the tranny.

cheers

Gary
79 MGB
gnhansen

Gary have a look at that thread:

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=71&subjectar=71&thread=2009032012523718099


I think synthetic oil is not suitable for bronze bushing in gearbox and it needs some friction to have OD operating properly and synthetic is non-efficient there.

JG

PSSearch archive this topic is frequently mentioned
Jean Guy Catford

It *should* be engine oil, of what ever grade is correct for your local climate, cold zones use lower than 20W/50. 90 gear oil *can* be used, in fact it is specified for the V8. It has a very similar viscosity to 20W/50 so doesn't cause stiffness or any other problems, but it does have that smell. Wouldn't mix the two, though.

Sounds like when you have identified the source of the leak it will almost certainly need draining to fix, so clean the filters and replace with engine oil.
Paul Hunt

I ran my o/d on synthetic for years and it worked fine. I rang Castrol tech and they said no reason why not. It was changed when the layshaft bearings failed and I have used 20/50 since then.
Stan Best

I have used 30 weight non-detergent oil over the past years/6000 miles, and so far seems to be OK.
Erick Vesterback

This thread was discussed between 12/05/2009 and 14/05/2009

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