Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Transmission oils for traditionals

Dave
As ever a superb article on the rare art of oils. You will recall that I have just upgraded to the Red and Grey Roadster and interestingly enough the previous owner replied to my letter with some background on the car. He kindly told me that he had some noise from the rear diff at some stage which was cured with a double dose of friction modifier. He also recommended an annual change of diff oil in this car, so I will put my new skills, thanks to your post, to good use. Further, have you found any problems with the rear diff oil change, I believe it is very viscous.

Lightsphere
Thanks for the compliment
My diff has a slight clicking noise when reversing, but since the service I haven't noticed it. I must pay more attention. There's still a few cc's of friction modifier left over so I'll put that in if necessary. The actual oil change is 'easy' but takes a bit of time since it's a slow drain, and slow fill. It would be a bit quicker after a run, but I did mine cold due to time constraints - note the ambiguity - I didn't 'have time' to go for a blast first, but had to wait while it drained. However you can get on with other stuff so it's not lost time. The old oil was much darker than I expected, and I intend to do an annual change now. When the semi synth has gone I'll probably go to fully synth, because I really can't detect what's different in the specs apart from the obvious bit in the title........

Is the purpose of removing the level plug on the diff to see the new oil dribble out, then you know it is full.

Well, first rule of transmissions is, always remove the level plug before the drain plug. Because if you do it the other way round and the level plug won't come out - you're stuffed.
This axle is unusual in that most drain plugs are on the bottom pointing down, whereas this is one of the rear cover bolts.
Refill through the level hole and - quite right - when it dribbles out it's to level. Because the rear will be jacked up - unless you have a pit, you need to lower it to get a true level, before refitting the giant level plug (using an adjustable spanner).