I have a Supercoupe with the Mazda designed manual 5-speed trans, model number M5R2. I understand a very similar trans was used in 5.0L F-150s in the late '80s-early'90s.

I recently had my trans rebuilt, part of the rebuild was an "upgrade" to the solid brass synchronizer blocker rings used in the F-150 trans. Now the car is a real pain to get into gear.

I am thinking I might be using the wrong type of fluid for these new syncho's. What is recommended for fluid in the F-150 manual 5-speed trans?

 

im not sure what is recommended, but i use regular gear oil in mine, no synthetic, nothing special. good luck with the problem!

 

My 92 calls for ATF. I know it sounds crazy,but it is true. Most of the manuals with aluminum cases use atf. I have heard of people putting 30WT motor oil in them,but I dont know of any benifits of doing this.

 

The SC owners manual calls for Mercon III ATF. I had thought perhaps the different synchros in the F150 might call for gear lube or something.

I have tried Mobil 1 ATF, Wolfshead Mercon III, and GM Synchromesh manual trans fluid. The Synchromesh helped a bit, but it is still a pain.

The shop that built my trans recommended the straight 30Wt mineral based (non synthetic) motor oil for summers, or ATF for year around driving.

I think thicker fluid might help because it shift nice over the winter when it was 5 degrees out.

Donate54 how long have you been using gear lube in yours? I was thinking of trying it, but I was afraid that something that thick might not get in tight places and lubricate the bearings like it should.

 

well my tranny has had a very very small leak since i bought it (almost 4 years ago), and when i first bought it i drained all the fluid out and refilled it with gear oil. since then, every 2 months or so i open the filler plug back up and add some more to compensate for the leak. tranny has not given me any problems since I bought the truck. hope this helps, good luck!

 

Yes, I can reassure you it is Automatic Transmission Fluid.

 

i bought the truck used so i dont have the owners manual. you guys think i should put ATF in my tranny next time i need to fill it up? thanks!

 

Mine is an M5R2 also and it does require ATF. It took me a little research to find that one out.

 

this post was started a long time ago, but im just bringing it back up to let you guys know that you were right about the ATF in the tranny. just changed the fluid in mine today as soon as i found out i was wrong. thanks for mentioning it!