The AX-15 fluid issues are well documented on this and other forums, but I think my experience is worth looking over if you are considering a fluid change on your AX-15.

I recently drained my old MT fluid from my AX-15 as part of the new ownership preventative maintenance. The fluid appeared to be very 'worn' and I have no reason to believe that it was not original. That being said, the tranny shifted fine and seemed to be in good working order. When I swapped fluids, I used Napa Gear oil, 80w-90 (Gl 3, 4, & 5 compliant). This turned out to be a huge mistake as the synchros are brass and many gear oils have sulfur in them, which eat at our 'yellow metals' *. A day or two after putting in this fluid, I lost 2nd gear and all shifting was much more labor intensive (if you know what I mean). I immediately bought Red Line MTL which is yellow metal safe and just put it in. Remarkably, my shifting is now smooth again and feels like a new transmission!

I highly recommend this fluid and will only use it in this tranny from here on out. I could not find it locally but was able to find it online at either summitracing.com or myoilshop.com. That being said, please research this topic on this forum. There are other gear oils that are said to be just fine for the AX-15 (e.g., an Amsoil, Pennzoil Synchromesh, and possibly others). I can only speak from my experience.

s

* Please note that I know how to swap tranny fluid so the shifting issue with the Napa oil IS NOT the result of impropper fluid changing procedure.

 

I may be misunderstanding what your saying, but "Napa Gear oil, 80w-90 " sounds like differential oil, which is way to viscous (thick) for a manual transmission. The recommended oil is "SAE 75W-90 API GL-5" which is for manual transmissions and transaxles.

 

Actually this is incorrect.... At operating temperatures a 80w-80 and a 75w-90 will be the same viscosity. The difference would be at temps approaching 0 degrees, then the 80w-90 would be thicker than an 75w-90. But the AX-15 does specifiy gear lube as its lubricant... But ABSOLUTELY no GL-5 lubes. The high sulfur content will eat the bronze syncros in the transmission.

 

So what brand and weight would you recomend for Va weather Whowey?

 

I am the first to admit that I do not know the ins and outs of oils, but I do follow the FSM really well! I tripple checked before abiding by all details specified. I'll defer to Whowey on this as he is an authority on this matter.

s

 

Virgina doesnt experience the extended periods of sub-zero temps that more northly climates do. A 75w-90 GL-4(like the FSM recommends) will be just fine for your enviroment. Pick yourself a good quality brand and your transmission will be happy... Just avoid any fluid that claims it can meet specs that vary greatly... Like saying it meets the needs of trannys needing 75w-90 and ones needing ATF.....

 

I added synchromesh to mine when I did my clutch in december. so far I have had no problems and my cold weather/cold start shifting seems to have gotten a lil less hard/notchy