Luckily I own a Miata, and have a MIATANET login!!!
http://www.miata.net/garage/trans/everything.htmlYou can't handle the truth! Fill the shift turret with whatever you want. Bacon grease, motor oil, gear oil, Gibbs Orgasmotronic 2000 Shift Turret Oil, it is nothing more than some balls and springs and a $3 bushing. Replace the bushing early and often and nothing else about the shift turret matters!
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(Next-Day Edit: The above post was sponsored by my friend's homemade cherry wine, and is NOT entirely true or my official recommendation ... )
A better answer ....
Blah Blah Shift Turret Blah:
1. Replace the bushing early and often. LOOK FOR AND RETRIEVE OLD BUSHING CHIPS FROM INSIDE THE TURRET.
2. The oil really isn't that important, but if the internal seals leak, your turret oil will end up IN the gearbox - so why not used whatever is in the gearbox?
3. If your turret oil keeps going down and it isn't spilling OUT, then your internal seals are leaking. I wouldn't pull a gearbox just because of this - just refill with oil regularly, or just use grease!
4. If you don't seal the shifter boot to the turret (with a good gasket or RTV), then oil can slosh out and make burning smells on the exhaust or make you think you have a leak. If you use RTV, make it THIN ... the shifter lateral detents and springs are IN the shift turret, and the tolerances are fairly tight - you don't want RTV blobs down there.
5. If you are unhappy with your side-side shifter behavior (shifter not springing back to Neutral as strongly as you would like, or you have to slap too hard right to get into 5th, then the issue lies in the turret. This is easily "tuned" without tearing into the box.
