transmission fluid...

[90mustangfan]

I have a stock T-5 trans in my stang...It grinds inbetween shifts when the trans is cold....when it warms up it stops grinding, Im going to change the fluid, what fluid should I put in, and is there anything else I can put in to help with the grinding....I know the snycros are going but is there anything kind of fluid that will help it...Somone told me to put a teflon type of fluid, and that will help with the syncros and stuff...Is that true...

 

[Mustang5L5]

ATF Dex 3

Replace the synchros soon before the grinding starts to damage the dog teeth on the gears. It will just make it more expensive.

 

[jackchan]

ATF Dex 3

Replace the synchros soon before the grinding starts to damage the dog teeth on the gears. It will just make it more expensive.

ditto!

 

[gt40_2003wes]

mine does the same thing buit i think i just need a rebuild.

 

[maverick0716]

ATF. You can put synthetic in if you like...that's what I run. Don't listen to anyone who says to use gear oil or motor oil....some transmissions require those, but not T-5's.

 

[Duro5341]

^^^^^agreed.........

Either Dex III, synchromesh...........oil, and gear oil will kill your T-5

Duro

 

[srothfuss]

ATF. You can put synthetic in if you like...that's what I run. Don't listen to anyone who says to use gear oil or motor oil....some transmissions require those, but not T-5's.

That is what I was going to say! :Word:

 

[HISSIN50]

Some T5's do require gear oil, just not the one in an '89.

SInce it happens when cold, I would take Mav's advice and try some synthetic (not as a fix, but till you can get inside the box). It might help since it flows better cold, or it might make it shift worse. Hard to say. Worth a try IMHO.

Good luck.