Datsun Roadster Forum-311s.org

Greg. Even though I have Redline on order, after seeing this thread I looked into Swepco 201 but found that it comes in several weights. What weight are you using/recommend? I'll continue with the Redline but will keep Swepco in my information bank just in case.

Peace,
Pat

Had my '69 5 speed repaired at a transmission shop recommended by Ross from Sports Imports... they sent it back with this for the fill:

GM 10953509 Synchromesh Fluid

Semi-synthetic with friction modifiers, talked to the tech and that's what he recommended for roadster transmissions.

Been running it since 2019 with no shifting or synchro issues.

Pat, I wish I could tell you for sure, but I no longer have a bottle... when I get more time I'll see what I can dig up. The RP was 75/140... some have had concerns about leaking, but we'll see.

Correct me if I am wrong, but 75-140 should work fine, the 140 means it stands up to higher heat real well, but at normal temps is the same viscosity as 75-90.
I tried 110-140 one time, but it was so thick that it warmed up too slow, and the grinding in the first couple of minutes was unpalatable, excruciatingly painful on the ears. (and on the pocketbook if left that way)
I also tried RedLine MTL, but it is definitely thinner, as it left a lovely, perfectly centered, triangular red swath down the bottom side of the car going towards the rear in no time flat. (The MGB version of rust protectant application!)

In case you’re interested in this product like myself, part # has changed to 88900399. It’s $18 plus change on Amazon.

Syncromesh is really for the fiber insert brass blocker rings of the 90 trans although it can work in about any manual too bad we could get some like that
At 30-40 degrees it is as runny as water, that may have been the early stuff though , some in Cal. refused to service it saying the toxicity was bad to be around