I went down to my local Oriley auto parts today get some transmission fluid and they tell me that for my '93 f350 7.3L diesel manual 5 speed I should use dexron mercon. I did the fluid swap and now she shifts like hell! Does anyone have a prefrence or expierence with this???

 

Dexron should be right for the ZF 5 speed. I've never had one shift worse from a fluid change, but I definitely have had it shift better when I used Royal Purple Synchromax.

Mike

 

I use gear oil??

 

I just checked the Chilton to make sure. It says Dexron II (Mercon) for all 5-speeds and 85w-90 gear oil for 4-speeds. Of course, being a manual tranny, it's probably not all that picky.

I've used the Royal Purple stuff before in several vehicles and always liked the results.

Mike

 

I put type F in mine with some Slick 50. When i bought it i just knew it needed some type of atf, wonder how much it really matters. Any idea what was in there? synchros could be bad and the PO may have put some 10-30 or sae30 in there to help em out.

 

this is a good solution to bad synchros...my reverse synchro is on its way out...i threw some SAE30 in there....helps out a lot.

 

i went to ford before i changed mine when i was told by some guys to use ATF in a manual trans. was told by ford to use Mercron 5 in the ZF-5 so i got valvoline mercron 5 and havent had a single shifting problem

 

Thanks all may be some issues with trans then looks like I will be putting 10-30 back in her if it will help improve shifting

 

Dont fill it completely with 10-30.....it will make it really hard to do anything lol...that oil is a little thick to be used in a transmission that doesnt build a tremendous amount of heat like an engine does.

 

What do you do? Mix it with something or just leave it low?

 

DO NOT run anything else but ATF in a ZF5!

The clearances in this tranny are very very tight, thick oil will not get everywhere it's suppose to....

 

x2

Old manual transmissions take thicker oils, newer ones take ATF.

hardwaterfreak, describe shifts like hell??

Aune163rd, does 1st work fine? Is reverse grinding the problem you're having? This could be the clutch not completely releasing or the pilot bearing dragging. The latter was the problem with my truck.

 

it was just tough to get into any gear, once it went it in didnt grind.

 

If the trans has problems its clearences are obviously not as tight as they should be thus the use of heavier oil. 5-20 is about the same viscosity as atf, 10-30 would be a step up. The lighter oil is to help the trans stay cool due to it being aluminum case, same thing for alum. t-cases. Obviously if you put to thick of oil in, you go to the other extreme and you wont be able to get it into gear when its cold.

 

Before I put the SAE 30 in, it was tough to get into gear in any condition...now...its just tough to get into gear when its -20* outside.