Can someone offer some advice please.
I have nearly finished reconditioning my MGB 4-synchro Gearbox with Overdrive.

My question is:- The Haynes manual recommends that I use 20W/50 engine oil. This seems to be difficult to get hold of. I am a little concerned about using 10W/50 as it is a little thinner whereas gearbox oild is usually a little thicker. Am I unduly worrying about this. What have other used.
Thanks

Hi Peter.

I cannot comment on oil choice for this particular application as I am not familiar with your gearbox. I suspect however, as you do, that you should go for the recommended grade - this is certainly true for older engines which could suffer if given thinner, modern oils. They will, at least, consume the oil at an alarming rate! Gear boxes might be affected in other ways - good chance the overdrive will struggle to operate properly.

Are you 100% it's 20W/50 that's needed?

If you are after 20W/50 oil, you can't do much better than Miller's Classic Sport 20W/50 oil which is semi-synthetic and available from the following at a great price: http://www.james-sherlock.co.uk/ . I bought some for my old Pinto engine; cost around £24 for 5 litres collected, although they also do mail order. The best price I found, by far.

Hi Peter
You are right that 20w/50 is the correct grade. It is not as difficult to get hold of as you may think. Duckhams still do their Q oil and I also found some in my local car accessory store. You may have trouble finding it in places like Halfords but ask in your local store and they should be able to help. If you have an MGB engine, you should be using 20w/50 in there anyway.

Thanks for the replies.
I managed to get some 20W/50 from Halfords.
It is their classic oil and is not recycled as some are.

Thanks again