I put Lucas 75w90 to change out my manual gear box oil. Not terrible but noticed no difference in shift smoothness. I haven’t played with oils in a while. I remember many years ago I put Royal Purple in my E39 M5 gear box and I really did feel smoother shifting afterwards.

Anyone try Royal Purple synchromax in their manual gear box or other aftermarket oils with noticeable success?

http://www.royalpurple.com/product/synchromax-manual-transmission-fluid/

 

Which car is this for and what kind of problems are you having? The 6sp manual in my -06 997 C4S was the best manual I ever had. Like a hot knife through butter even with a B&M short shift kit installed and the factory transmission oil.

 

There's only one oil that should be used in a 997 gearbox and that's Mobilube PTX. Nothing else works as well.

 

I put Lucas full synthetic 75w90 gear oil because of age. The oil that came out was pretty clean. No issues but no difference either. I had a good experience with royal purple so just asking if anyone else has also tried. The synchromax in particular and not the standard royal purple 75w90.

 

I recently changed mine ('07 C4S) with Red Line Synthetic as it was getting progressively "notchier" (is that a term?) in my 2-3 and balking a bit more when cold. I've seen a substantial improvement in both areas.

 

Good to hear. I haven’t tried redline gear oil yet. It was usually royal purple or redline and always seem to just pick royal purple.

 

same here, using redline and things are way better cold.

 

which redline gear oil did you use? 75w90NS (non slip) GL5 gear oil or the MT-90 75w90 GL4?

 

75W90NS GL-5 Gear Oil is what my Indy used.