Has anyone tried synthetic lubricants in their transmissions or differentials?

I own an '85 BMW with a 5spd that has 225k on it. With that kind of mileage the linkage is quite old and some gears are hard to get into. All the enthusiasts rave about the Redline MTL in these trans. I put some into mine and it completely transformed the shifting.

I'm not sure if this is a result of being brand new and things haven't yet broken-in properly, but sometimes the Fit transmission feels notchy and difficult to get into gears.

I'm curious if the Redline MTL will make it buttery smooth like it did with the BMW. I'm going to wait until the first oil change before I change it and I'm currently only at 1.7k.

 

Honda literature states that other fluids might have the wrong balance of slipperiness and friction.

Obviously a slick fluid would promote better shifts and less gear wear. But some friction is needed, as well, for the synchronizers. It's a fine line.



The Honda MTL is actually a very good tranny fluid. I changed it in my MT CR-V at 15K miles. Because I spilled some I topped off with an ounce or two of 5W-20 synthetic motor oil (which felt significantly slicker than the Honda MTF). No problems so far.

 

In my experience Redline would be fine.

People with grinding shift too hard and damage the syncros over time. Just don't shift hard because there is no reason to.

 

Redline has also caused many problems in Honda auto trannies as well. i would stay away from Redline in Honda trannies. It seems to be a hit and miss.

Honda recently improved their MTF, stick with OEM. It performs absolutley well. If not, Amsoil Synchromesh MTF has been getting great reviews.

 

Honda seems to engineer high-spec fluids that are a integral part of how their systems work.

I would NEVER use anything other than Honda MTF in their manual trans, or Honda Z-1 ATF in the Acura's auto-box. There are too many stories out there. Often problems occur a year down the line...

Same goes for the blue Honda coolant. I have heard it doesn't mix well with the "green stuff". I don't know if it's OAT type (Dexcool) or not.
I don't actually care. By doing my own changes I save on the labor, so I treat my cars to the Good Stuff!

 

I used to run GM Synchromesh FM in my S2000 and preferred it over the Honda MTL, I've been waiting to see if anyone here has switched