Manual transmission lube

[ksierens]

I have been researching what fluid to use in my trans, and frankly, it is getting over whelming. Redline, Driven, Royal Purple, Brad Penn, Lucas, Valvoline ...

I will just be cruising with my car, so does it really matter other than not using GL5 oils?  I was thinking about just using Valvoline High performance gear oil SAE 80W-90, but looking for arguments against it.

Thanks, Kurt

[Chryco Psycho]

GL4 80-90w is what I would be using , brand is your call , I use Castrol mostly

[303 Mopar]

I use Sta-Lube. Synthetic is too thin for the synchros and leaks.

[RUNCHARGER]

The Valvoline will work fine.

[anlauto]

 

[dodj]

Synthetic is too thin for the synchros and leaks.

I'm no 4sp guru, but I thought the thinner stuff was better for synchro operation? 

[Marksmopar1]

I have always used 80-90 Gear oil...never an issue.....

[303 Mopar]

Synthetic is too thin for the synchros and leaks.

I'm no 4sp guru, but I thought the thinner stuff was better for synchro operation? 

Here is more detail as to why...

[Chryco Psycho]

not so much to do with viscosity but Synthetic is too slippery , any GL5 rated gear oil is to slippery for the syncro to grab

[Arctoad]

Royal Purple 75W90 awesome. Expensive though, $26.00/Q, 4 Q needed.

[dodj]

I use ATF in my 833. Works far better than 75/90. I originally put 75/90 in my 833 but the synchros did not work well. Little bit of gear grinding...unless you shift really slow. Swapped in ATF and it shifts beautifully.

Shifts better than 75/90 and after 25 years of hard shifting the insides last year were pristine.

Which is why I figured thinner is better for synchros.

[ksierens]

Thanks for all the recommendations.  I ended up going with Driven conventional 80w90 lube.