Manual Transmission Fluid

Ok, I have a question about what some of you are running for fluid in your manual transmissions.

The MTX is out of my 99 getting an overhaul. The first time it was the shift fork in the 70,000-80,000 range. Pretty much not long after I got it. It was found that the spider gears were also toast. This time at 184,000 I pulled it out because I thought I had a bad synchro but found out that it might have been the bad transmission mount. Anyways, it was found that the spider gears are toast again and the transmission could use some bearings.

So when I get my transmission back I want to know what has worked for some of you guys. The manual recommends regular old mercon ATF. So I figured I would run synthetic stuff. I don’t really know if it did any good or bad running it previously. I just noticed the manual also says 75w-90 gear oil can be substituted. Has anyone gone that route? I picked up some Synthetic stuff because that was all I could find in that weight at the moment.

In an unrelated issue, the actual reason I picked up the 75-90 is because that is what my wife’s 2007 Fusion calls out for. (Yes, its a manual.) The only issue is that the manual states non-synthetic. Would synthetic be an issue, should I follow the manual, or maybe call a stealership and find out for sure?


I run 75w-90 synthetic gear oil from mobile 1. Great stuff and i think it gives you a better protection. Only thing is if you live in winter it might get a little thick and gel up.

Same here

I have Pennzoil Synchromesh in mine

Ya this another huge one guys use.

I have always liked the Mobile 1 stuff. I was running the synthetic ATF before, but when I get my transmission back I think I will switch to the 75w-90.

I have another question about filling it with fluid. I always used the top plug which to me looked like the fill plug. I would just pump fluid in until it started to seep back out like a differential. But I just read in one of the numerous manuals I have that it is supposed to be filled through the speed sensor hole? Is this correct? Is there some type of a fill line on it? I don’t have my transmission so I can’t look at it.

And one more about my wife’s 2007 Fusion. It is in need of a transmission fluid change and it looks to have the same MTX transmission. I’m not certain and I am not sure where to get the specs on what is in there, but it sure looks similar. Is anyone familiar with these or know of a site where I can get some info?

Thanks again!

Yes the fluid is suppose to be on the top of a Vss hole for the zx2. I use a huge funnel to get to it.

For the Fusion I would assume the same but you might want to look over a manual to double check.

I’m not sure on the fusion either, but from what i can tell from my factory manual I believe the “full line” for the manual tranny is the vss gears

you are correct mellow