I'm close to finishing the auto to manual tranny conversion on my 71 240Z. It's a 5 speed out of a 78 280Z. Since I bought the transmission at a junk yard with no way of knowing it's condition, I took it  to a reputable transmission shop to get it looked at before I put it in. They replaced one bearing and said everything else is good. So, do I fill it with whatever is originally recommened, or have any of you had better luck with anything else. I live in Iowa, so it only gets driven in warm weather and put away in the winter. Thanks.

True GL4 oil. Not GL5.

The Datsun transmissions seem to do very well with Redline's MT-90 oil.  Better than a generic 90 wt., for sure, with a transmission that has some miles on it.

Pennzoil Synchromesh. You need an oil that works with yellow metals such as Datsun's brass syncros. Redline works too.

 

Chuck

 

Pennzoil Synchromesh. You need an oil that works with yellow metals such as Datsun's brass syncros. Redline works too.

 

Chuck

 

I have also used both of these. Redline currently. I have developed a leak between the engine and gearbox.

Not too bad. I think it is the gearbox. If so I don't think any issue with the oil. My seal is the origional from 1978.

If you do still have your gearbox out I would change the seals anyway.

Edited March 2, 201511 yr by lumens

Yep Redline GL4 75-90. What I have always used.

I have Redline MT-90 in my 5 speed. Penzoil Synchromesh is the only other oil that I know of that is a GL4. Don't use anything else or it will eat your syncros.

(There is sulfur in the GL5 oils and it destroys the bronze synchronizer gears in the transmission.)

Thanks for all the great advice! I think I'll go with redline. 

 It's the NS you need to look for as in Redline 75w/90 NS  (no sulfur)

Redline MT-90 or Brad-Penn Multi-purpose Classic. Both are GL-4.

 It's the NS you need to look for as in Redline 75w/90 NS  (no sulfur)

 

FYI, in Redline-speak NS means "No Slip", i.e. no added friction modifiers (typically used for clutch limited slips). It has nothing to do with sulfur content.

 

Furthermore, the NS stuff is GL-5, not the GL-4 that Z-car transmissions call for.

Thanks Leon,  I gotta stop taking forum opinions as facts. I think I'll just go out and drain my tranny right now.