New gear oil formula
 

I changed my gear oil for the first time about 2 months ago using Motul 300. After the change, I had some difficulty getting into second gear when cold and occasionally did not go into other gears as smoothly as I would like. Keep in mind that "cold" is a relative term as the change took place in late August. I was not looking forward to going through the winter with product so I thought about trying something different.

I used to have BMW's with manual transmissions and used Royal Purple synchromax with great success. I knew this was too thin for the BRZ transmission but I had several quarts in the garage. Pentosin MT fluid has been used very successfully on some BRZ's and is actually the factory fluid on BMW's. So I had an idea. I drained just over 1 quart of Motul out of the gearbox, put the drain plug back in and then filled with Synchromax. The car was dead level as I have a lift that raises the whole car at once. I filled until it weeped out of the fill hole. Then to make sure it wasn't over filled, I drained about an ounce or two using a mity vac oil change pump.


After putting the panel back in place and cleaning up my mess, I took the car out for a spin. I wasn't expecting that much change but I was wrong. I have never felt this gearbox shift this smoothly. Not just into second gear but every other gear as well. There was no placebo effect here. It was dramatically better. Note that it was about 65 degrees when I took the car out this afternoon and I will be interested to see how it does in the morning when it is scheduled to be in the upper 30's. I also have my last track day of the year next Saturday so I should be able to see how it does under both extremes. Will let you know.

Interesting experiment.

Please keep us posted on the results ....:)


humfrz

So far so good. The big test today was to see if I could downshift from 3rd to 2nd without double clutching as I was leaving my house this morning. Normally, this is very difficult until the engine and transmission is fully warmed up. However, no problem this morning at about 38 degrees. I am still very optimistic about the change but will let you know if anything changes.

I can't seem to find any info on the syncromax, like the api rating. Or even the label on the back of the bottle. Also "Synchromax is recommended for manual transmissions that specify an automatic transmission fluid."
here is the cross reference guide from royal purple http://www.royalpurpleconsumer.com/a..._Reference.pdf
Good luck!

From my own experiences with various fluids, this will likely work well for you. It should be pretty close to the MTL/MT-90 mix that I tried.

After searching online for RP Synchromax specs, I've found a few people saying it is indeed GF4/GF5 rated, and safe for yellow metals, but haven't been able to confirm that with actual specs from RP.

Just remember, just because a fluid "feels" amazing, doesn't mean it's sufficiently protecting.