Redline MT 90

[donh1969]

Recently had the transmission oil on my 1968 Jaguar E-type replaced with Redline MT-90 ( 70W80) . The mechanic who changed it ,suggested that the MT-90 could also be used in the diffential since according to the label on the container it was suitable for transaxles. I contacted Redline and asked them if it was safe to use MT-90 in the differential and they advised me that I should be using their 75W90 differential oil for the following reason:
" A high offset hypoid ring and pinion differential requires an EP, extreme pressure type gear oil. The EP protection offered by the MT-90 is greater than necessary for a GL-4 though not quite that of a GL-5. The issue that could occur with continued use is accelerated wear of the ring and pinion gears"

What I would like to know is it really necessary to remove the MT-90 from the differential.

BTW: The MT-90 made a very significant improvement to shifting gears!
Thanks

 

[bulwnkl]

I'd do as Red Line recommends.

BTW, the 'weight' of MT-90 is 75W90, not 70W80; that's MTL.

 

[wantin150]

MT-90 is 75W90. Their MTL is the 70W80. Personally, I wouldn't use the MT 90 in the diff and would drain and replace with GL5 rated fluid. Is there an owners manual for that thing? Photos of the car would be awesome!

Edit: I was typing as ^^^^ replied or I wouldn't have repeatedthe weight.

 

[mechtech2]

Conventional differentials use hypoid gears, which have highly loaded contact points that actually slip a bit.
This is very hard on oil, and is why special lube is always required/spec'd.
Dump the Redline from the diff.

If you want to save it, after you saved it let it run through a couple of stacked coffee filters in a funnel. This will take forever but will get it nice an clean so you can use it in the transmission. If you are richer than the rest of us, just dispose of it.

 

[sprintman]

Do not use MT90 in the diff, change it to 75W90 ASAP. Oh and get a new mechanic as well.

 

[donh1969]

Thanks to all who replied to my posting . I think the message is loud and clear.

Don