Differential Oil Recommendations

[AUSMHLY]

You'll have a tough time finding straight 90w. Amazon has a few used in marine and other special applications.

Moss motors sells a straight 90W GL4, Dynolite. Description:
Our classic cars require special fluid and oil formulations, in particular, gear oil. Newer GL5 oils have too high of a sulfur content which erodes yellow metals such as bronze or brass, which are commonly used in British applications. Our cars require a GL4 type oil and this Dynolite Gear Oil is perfect for our classics.

 

[AUSMHLY]

Video GL4 vs GL5
https://www.youtube.com/watch?v=XHwULF-EdtQ

 

[steveg]

Moss motors sells a straight 90W GL4, Dynolite. Description:
Our classic cars require special fluid and oil formulations, in particular, gear oil. Newer GL5 oils have too high of a sulfur content which erodes yellow metals such as bronze or brass, which are commonly used in British applications. Our cars require a GL4 type oil and this Dynolite Gear Oil is perfect for our classics.
View attachment 60908

Not that hard to find after all! :wink-new:

 

[RAC68]

Hi All,

If I am not mistaken, at some point the use of bronze and/or brass in the transmission was discontinued but I have no understanding if bronze or brass was used in the rear. Can someone verify my understanding and enlighten me on the presence of these materials in the rear?

Thanks,
Ray(64BJ8P1)

 

[Bob_Spidell]

Hi All,

If I am not mistaken, at some point the use of bronze and/or brass in the transmission was discontinued but I have no understanding if bronze or brass was used in the rear. Can someone verify my understanding and enlighten me on the presence of these materials in the rear?

Thanks,
Ray(64BJ8P1)

Posted earlier: "GL-5 may be problematic in a Healey rear-end. There are admonitions around that GL-5 has Extreme Pressure--EP; sulfur and phosphorous--additives that may damage brass and bronze, and David Nock informed me that Healey diffs have bronze thrust washers in the spider gears. David also added that he's used GL-5 for many years and has not seen any damage from it."

The gearboxes have brass shift forks, and earlier boxes have brass synchros (later have steel). I don't think the shift forks would be affected much, as they don't experience the HP shear forces that a diff would.

 

[RAC68]

Thanks Bob,
Ray(64BJ8P1)

 

[steveg]

Posted earlier: "GL-5 may be problematic in a Healey rear-end. There are admonitions around that GL-5 has Extreme Pressure--EP; sulfur and phosphorous--additives that may damage brass and bronze, and David Nock informed me that Healey diffs have bronze thrust washers in the spider gears. David also added that he's used GL-5 for many years and has not seen any damage from it."

The gearboxes have brass shift forks, and earlier boxes have brass synchros (later have steel). I don't think the shift forks would be affected much, as they don't experience the HP shear forces that a diff would.

Probably the EP additives are helpful in the rear end gears. Since neither Nock nor John (of GearBoxVideos) have any problem with GL-5 and yellow metals, I plan on continuing using it in my diff. John says the GL-5 oil would have to boil before it did anything other than discolor the yellow metal. I think we have it on good authority that there won't be any problems from GL-5 in our diffs.

The discussion of using it in transmissions isn't really relevant for the Healey trans as you are using motor oil in there anyway. I'll continue to use Red Line MT-90 in my Toyota trans.

 

[Legal Bill]

Hello everyone. Having observed a recent drip from the pumpkin, I'm going to change the diff fluid. At the same time I'm installing a new drain plug that will be wrapped in teflon tape. I'm bringing this discussion back to the top to discuss what fluid to use. I'm asking the group to revisit this issue due to the claims that GL5 additives (sulphur) cause damage to bronze, copper and other bearing and thrust washer metals. Because of these claims about GL5 fluids, I'm inclined to avoid them. The Moss Dynolite 90 seems to be the right product for the Healeys. It has the exact manufacturer recommended viscosity and the lower sulphur/phospate content. I suspect it is for hypoid gears, or else Moss would not market it as such. I guess I could be wrong about that. Anyway, is anyone aware of any alternative that meets these three concerns (hypoid safe, 90 weight, lower sulphur content)? I also wish to avoid products that are more likely to seep out of the pumpkin or drain plug, so I guess that is four concerns. I look forward to your contributions to this discussion.

 

[Legal Bill]

Probably the EP additives are helpful in the rear end gears. Since neither Nock nor John (of GearBoxVideos) have any problem with GL-5 and yellow metals, I plan on continuing using it in my diff. John says the GL-5 oil would have to boil before it did anything other than discolor the yellow metal. I think we have it on good authority that there won't be any problems from GL-5 in our diffs.

The discussion of using it in transmissions isn't really relevant for the Healey trans as you are using motor oil in there anyway. I'll continue to use Red Line MT-90 in my Toyota trans.

Steve, I didn't see this post of yours from 2019 until I posted my message above. Then it popped right up. I didn't want you to think I did not consider your comments before posting. I just didn't see them.