M/T fluid level question
 

First off, I've done a search under several different keywords and haven't found the answer.

First a little background: About 9 mos. ago I changed my manual tranny fluid from the stock to Mobil1 Gear oil. However, this winter I noticed second gear would grind when it's cold. I worried that I may have been a little short on fluid.

So today I added about 1/3 qt. This is in addition to the 3 quarts I put in when I changed it out. My question is, can you overfill the fluid on a Manual tranny? After all, won't any excess simply come out the fill hole since it's pointed down anyway?

Any thoughts are welcome.

the fill hole is the level you want to fill it to. when fluid runs out you are full.

Try replacing the Mobil1 with Redline MT90 tranny oil. I've used the Mobil1 synthetic tranny oil before and wasn't all that impressed with it. Redline is much better and should help your second gear shifting problem.

However, Mazda manual trannies have a reputation for balky shifting in 1st and 2nd gear when they're really cold, no matter what. Try shifting slower. :D

Also I thought that Mobil 1 (75W 90) is not recomended for the G-Seires boxes. I read an email from a tech at Mobil 1 at www.probetalk.com years ago and the Gl-4 or Gl-5 ness or whatever iMobil 1 is, is not reccomended for our gearbox's. Research it more if it matters and I am not positive on why its not for ours...

I have to agree. My Miata is the same way, no matter what tranny oil i use. I guess it's just the way Mazda designs their transmissions.

I've been talking to a couple people about the clutch, as well as playing with it myself. TheMan says that switching to Motul brake fluid changed the way it works. I'm of the opinion that our clutch master cylinders are either a bit too small for the system, or they don't bleed them very well from the factory. The way they are grinding into 2nd is indicative of the clutch not fully releasing before you can shift. I think that's one of the reasons that they changed the clutch release arm on the Mazdaspeed. Better leverage ratio and probably better durability on the synchros. There are a couple other parts that they changed up at the master cylinder also to help keep pressure from bleeding off. All those parts will retrofit on our cars.