I’m going to be replacing my engine soon(ish) with the rebuilt Moss. I’ve been running straight Redline MTL for quite a long time with decent results. But I’ve been reading VW forums to find a suitable replacement fluid for that (my mechanic got water into it…don’t ask). I’m finding that a lot of people in warmer climates are having better results from mixing MT90 and MTL 50/50. I was considering doing the same in the Moss since Texas is certainly a warmer climate.
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Our son just put MT90 in his Gertag BMW to try to quiet a bit a trait called “Gertag noise”. The BMW (and others, as this trait is common to a lot of Gertags) guys say it is a bit stickier subduing the rattle. An extra 100 rpm does the same thing - son has a lightened flywheel, making it worse.
The Moss problem, as I’ve experienced it, is the gears (really a few different parts) need to slow on the 1-2 upshift and the ‘synchro’ (what passes for one in the Moss) needs to speed things up on the ddownshift. If the lube makes the hub grip on the downshift then it needs to overcome additional viscosity, which then resists the speed up! We don’t have brass to help the grip, so I’m for more “no-slip” and the heck with temperature issues.
The Gertag guys want a mix of redline ATF OR MT90 as they try to improve cold shifting - not an issue with most E-Types as we don’t winter drive or can wait until it warms up a bit. The Gertag people start with a 75w 85NS - since 75w140NS seems NA at this time. The “NS” is to stop slip on the rings. Those guys also need to watch the blending as some oils aren’t brass compatible.
How does one find out if oils are brass compatible?
You check the “GL” (I think) ratings. I’m pretty sure - just did all this within the last week, but was my son’s deal, so didn’t write it all down - the GL5 is not for brass, problem is most oils are now 4/5 compatible to save the number of products offered by makers.
Comparing and posting about different makes usually isn’t productive, as our cars are old and have unique issues. The point of my mentioning of the Gertag stuff was that farting around with manual trans oils is an old technique which is a time honored way to crutch problems (sawdust?).
The brass issue, I THINK is related to phosphorous. It is relatively easy to check out the brass issue by reading about the reline stuff. Redline may be snake oil, but they do seem to offer more viscosities and thus options.
I’d think the VW’s Erica mentioned have brass rings, so maybe not Moss interesting. Some ancient VW’s may have some non synchro gears, don’t know.
BTW, the Gertag rattle is neutral, clutch out - just like an input shaft or input bearing noise. A light flywheel changes the resonance, I personally believe, and the rpm sensitivity sort of confirms it. A tiny, tiny change in rpm makes it go completely away.
Not a worry in the Moss: the synchros are steel.
Typo, their name is Getrag. Used to work right next to the factory.
Usually I need double letters to effect a miss spelling…Son just got Verdestines for his car - don’t know how to spell that either…
Yes my VW has modern synchros, hence GL4 only. The fluid manufacturers may have modified their GL5 formulas after synchro problems manifested but I’m unwilling to take the risk, no reas9n to really. Both MTL and MT90 are GL4. From what I can tell the only difference is with viscosity.
So if I’m understanding correctly you think the lower viscosity MTL only is the best solution for a Moss?
Wisdom of the ages. I know manual transmissions, but I’m no Moss expert. I put the MTL in and it works OK, except for being intolerant of too high an idle speed. You said yours works OK also, so why not just leave it alone. Maybe there is some combination of oils that makes it better, but years of Jaguar posts seems to say to do what you and I already did.
Erica,
There is not a huge difference between MTL and MT-90. I would suggest just try full MT-90, and see how it behaves. I’d guess it will be fine, and, if anything, a bit better than MTL. Anything that increases viscosity should reduce noise and improve shifting.
MTL makes a HUGE difference over 20W in the Moss box. I first put it in my Moss almost 20 years ago, and I don’t recall MT-90 being available back then. If it were, I would have certainly used it instead of MTL.
Regards,
Ray L.
Our Moss always shifts well 3-4 up or down and 2-3 up, regardless of temp or rpm. The 1-2 up is better cold. This supports the idea Ray posited that more viscosity may help. As others have noted, 1 - 2 up is better if you “pause” when it’s hot. I’m not talkin’ real hot, as we’ve never got the thing super hot as yet. By the way, the German trans guys start with 75w 85NS (one quart) and finish with ATF for cold climates, MT90 for hot. I didn’t specify this previously.
Mine was pretty much the same way, pause always required 1 -> 2, 3/4, 4/3 were fine. 4 ->2 double clutch always and 3 -> 2 double clutch if speed much over 20mph.
It was rebuilt with new gears, cluster gear, syncho sleeve, layshaft, thrust washers and needle bearings so I’m hopeful things will be improved in a way that can be noticed.
Not that I need or want them, but where did the parts come from? Morgan people?
Needles and thrust washers from SNG. Layshaft from Welsh (cause SNG was out)
All the rest were ebay finds over the years. I put together a search list with part numbers and sat back and waited for emails.
The wear inside was not inconsequential. The end thrust on both shafts was twice max spec. Now dramatically improved.
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