My 5-speed and transfer case call's for mercon ATF, both had to be rebuilt at about 80,000 miles.......they put the Mercon back in and when the tranny gets warmed up the shifting is notchy, several people have told me the ATF is just too thin for tranny and transfer case gears and will cause failure earlier than thicker lube, I agree because they should not have failed that early, my question is what else to use in them, several guys on the mustang forums have tried Synchromesh in their T-5 tranny's and loved the results, also my friend that rebuild Toyota's said he allways puts non-detergent 30 wt. in them because it won't foam up and makes them shift buttuer smooth....what are you guys using???? because the mercon is coming out before my trans and case go again.......Thanks

 

I use Mercon all the time. We have had six different trucks with the M5OD and never had a problem.

Adrianspeeder

 

Put in some Mobil1 ATF and never look back. I am at 130,000+ miles and have used only mobil 1 and have had no issues at all.

 

I hope I can ask about a problem with a 1992 Explorer Sport 5 speed transmission. There is a rebuilt transmission in the car that is just one year old. It took 3 rebuilt ones to get one that did not leak. Is this common?

But now, after just a year in the car, 5th gear in this rebuilt is giving a very rhythmic clunk when driving in 5th gear. It almost disappears if you can let up on accellerating, or when not having to increase or maintain speed on a grade, but if you need to accellerate in the slightest, then the noise becomes very pronounced and rhytmic again.

It figures the 1 year warranty on this rebuilt transmission is just up. Any ideas?
Thanks

 

I am new to the list and a 3 week old 2000 F-150 owner (had an 88 a while back though).

Somebody recomended I try the GM Syncromesh (sp?) tranny fluid in my 5speed which was hard to shift, and would grind into 2nd and 3rd (truck only has 55k).

I replaced it this weekend after a long HW drive to get everything nice an hot. Gave it a long drain and filled it up w/ Pensoil Syncromesh (purchased at AutoZone) fluid b/c I didn't want to spend twice as much for the GM stuff.

Result? no more gear noise from the tranny and now I can shift as fast as I want w/ NO grinding at all! Plus, it is very easier and smoother to shift. I figure for the total cost (24$ for 4 quarts) I will do it once a year.

 

I have tried all the different brands of synthetic ATF including Rredline and Amsoil. I also tried Redline MTL and now I am using the GM syncromesh product and it is the best so far.

Regards

Jean Marc Chartier

 

I have 160k on my truck and the previous one went 300k(88 4.9 5 speed) The Mercon fluid was never teh reason of my failures. The 88 was just worn out, mostly the top cover plate and synchro. My 97 broke a tooth in second gear from what looks like a shock load. I can't explain that failure but it happened. I do know that the Mazda trans I have was never one to be speed shifted especially 1st to 2nd shifts.

The noise in 5th that silveraggie has sounds like a damaged gear that missed the first or second rebuild.

 

I also drained my tranny and replaced the fluid with Pennzoil Synchromesh, the tranny shifts butter smooth now with no grinding or hard shifting.......By the way I searched and found that the GM version is made for them by Pennzoil...same stuff.....I can recommend it to anyone, NOW does anyone have any suggestions on what to put in the transfer case in place of the water thin ATF???

 

I am not too sure what transfer case my 2000 has, but my mechanic years ago recomended I use 90w gear oil in the np208 in my bronco..it made that thing quiet and smooth, but you risk problems if the transfer case leaks gear oil into the fluid of the auto tranny...

 

I am not sure about the ford tcase but the newer GM's have a clutch pack in them that needs the atf to work right. I actually hope that the fords don't have that crap. It caused me nothing but grief in my GMC.