Choosing a Manual Transmission Fluid for my Mazda Protege

[1337]

I recently read through MetroMPG's post about the differences in transmission oil viscosity.:
Effect of gear oil viscosity on transmission efficiency (Metro owners take note)

I haven't changed the manual transmission oil since I've owned my Protege (so, about 10000 miles). I know the interval for replacing MT oil is often as much as 100k miles, but I'd like to be able to document when all my fluids were most recently replaced.


So, a few questions: First, as per MetroMPG's forum post, I'm considering using GM Synchromesh transmission fluid. Does anyone have any experience with this particular fluid?

What do other Protege owners use for manual transmission fluid?

Also, stupid question, where is the filler and drain on a 3rd gen Protege? Is it a straightforward job, or do I have to take a lot of stuff apart? The owner's manual explains how to take care of the fluid on the automatic model, but it seems to skip over MT transmission maintenance.

[1337]

Oh, just a note, according to autozone.com, the factory spec transmission oil is 75-90W.

[Daox]

I'm not sure of the differences between Synchromesh and other oils. But, I just put Royal Purple 75W-90 in my Paseo, and I can absolutely feel the difference in cold weather. Its definitely something to look into.

[MazdaMatt]

Hold up! Proteges do NOT have any manual tranny fluid change schedule in maintenance! It is expected from the factory that you will have the original MT oil for the life of the vehicle. I have spoken to people who have trailer queen race car Proteges and they use the stock oil. General concensus on the Protege forums i've been to is to leave it alone.

FYI, lighter oil makes for crisper, nicer shifts and faster syncro wear.

[bhazard]

1. Ive never heard of a MT with a filter.

2. I would not trust Autozoo's site for fluid specs. Both of my Mazda trannies (Festiva has an F series and the Capri has a G series) take auto transmission type fluid. Most modern manuals do not take gear oil.

3. MazdaMatt may have a point.

I personally am running Valvoline synthetic ATF+4 in my trannies. Its for chrysler autos but seems to be working well.

[1337]

MazdaMatt-

I bet in city driving with lots of shifting, the synchros would wear faster with lighter oil. However, I have a pretty unusual driving style. Most of my driving is very long stretches of highway. I often go hundreds of miles without shifting. I have taken I-44 all the way across Missouri (290 miles) without ever shifting out of 5th or pressing the clutch. I just turn on some audio books, set the cruise control for the speed limit, and let the car putter across the country.

With this in mind, I just can't imagine when I would give my synchros a chance to wear.