Ford Mustang Forums banner
1 - 20 of 34 Posts

·
Registered
Joined
·
601 Posts
Discussion Starter · #1 ·
Not trying to start an argument. I need to pick up some fluid for a fresh rebuilt T5. For the T5, I google and read and read. All I really see are people arguing. The builder just said "Throw some ATF in it" and I said do you recommend synthetic or just regular cheap ol' ATF. He replied with "Whatever you want, just use new fluid and check the level periodically"
So, do I want Mercon, Dexron, ATF etc. I have a bunch of this Castrol Max Merc but it states for GM vehicles.


Tin Automotive tire Automotive lighting Wheel Motor vehicle
 

·
Registered
Joined
·
457 Posts
T5 World Class calls for 2.5 quart Mercon III, I just refilled mine since I had to pull it to replace the rear main seal and used O'Reilly premium atf , been using it since I got this t5 a year or 2 ago. It says Mercon compatible and has been working fine for me.

Not sure on the Dexron, hopefully someone more knowlegable will chime in
 

·
Registered
Joined
·
1,568 Posts
I have used the Royal Purple Syncromax and oriley mercon 3 in my freshly rebuilt t5wc. Cant tell a bit of difference.
 

·
Registered
Joined
·
3,617 Posts
I've tried a bunch of different fluids in T5's over the years. None make a huge difference except 80w90, then it gets really hard to shift especially when cold.

just get some cheap dex/merc and be done with it. As if there was a such thing as cheap dex/merc. What is it now, $8/quart?
 

·
Registered
Joined
·
50 Posts
Manual trans just needs lubrication, not picky like the hydraulic systems in an auto trans. Don't get hung up too much on it.
 

·
Registered
Joined
·
457 Posts
I've tried a bunch of different fluids in T5's over the years. None make a huge difference except 80w90, then it gets really hard to shift especially when cold.

just get some cheap dex/merc and be done with it. As if there was a such thing as cheap dex/merc. What is it now, $8/quart?
For real! that's why I've been using the O'Reilly ATF, cheapest they have $6.99 quart!
 

·
Registered
Joined
·
499 Posts
I contacted Tremec appx 2 weeks ago ( email) asking what to use in my new TKX, since the Tremec fluid is Unobtainable at this time..
They sent back DexronIII/Mercon ATF........
I looked on line and Napa DexronIII/Mercon ATF was $3.95 a quart.....
 

·
Registered
Joined
·
457 Posts
I contacted Tremec appx 2 weeks ago ( email) asking what to use in my new TKX, since the Tremec fluid is Unobtainable at this time..
They sent back DexronIII/Mercon ATF........
I looked on line and Napa DexronIII/Mercon ATF was $3.95 a quart.....
[/QUO
I contacted Tremec appx 2 weeks ago ( email) asking what to use in my new TKX, since the Tremec fluid is Unobtainable at this time..
They sent back DexronIII/Mercon ATF........
I looked on line and Napa DexronIII/Mercon ATF was $3.95 a quart.....
Thanks, I may grab a few quart from Napa as backup!
 

·
Registered
Joined
·
162 Posts
I've mostly used regular run of the mill Dex/Merc. I've tried Synchomesh(which Tremec didn't recommend) and Mobil 1 Synthetic ATF(suggested by Tremec) but liked the way it shifted with the regular cheap Dex/Merc the best.
 

·
Registered
Joined
·
601 Posts
Discussion Starter · #12 ·
Thanks guys. I ordered the Napa premium ATF
 

·
Registered
Joined
·
8,054 Posts
If you read the back of the bottle it'll post what specs it meets. Most transmissions have no idea if they're in a Ford or Chevy because manuals are usually outsourced.
 

·
Registered
Joined
·
457 Posts
If you read the back of the bottle it'll post what specs it meets. Most transmissions have no idea if they're in a Ford or Chevy because manuals are usually outsourced.
True, T-5 were in Ford, Chevy, AMC and probably more!
 

·
Registered
Joined
·
4,349 Posts
I didn't say it didn't work, I said Tremec does not recommend it....
The TR-3550/TKO are spec'd to use GM Synchomesh pn: 12345349. The Pennzoil Synchomesh is equal. In fact I've read that Pennzoil makes GM Synchomesh. Is what I read true? Can't say for sure, but I'm sure that GM doesn't refine there own lubricants. They establish their required specs and put it out to bid to be made under contract.

When you search the GM number, the Pennzoil comes up as meeting the GM spec. So....equal.
 

·
Registered
Joined
·
499 Posts
I contacted Tremec because it seems the fluid recommendations are all over the board.. Read an article about people using Royal Purple and tremec did NOT test this fluid....
There have been recent recommendation updates by Tremec and it seems as if the push is more toward ATF types of fluids seems to be the direction...
I had a dodge with an 18 spline 4 speed ( Hemi) transmission in the early 70's... Worked part time at a service station ( thats when gas stations had a mechanic working) after school and on weekends.. The Motors manuals the mechanic had, said to use 140wt gear oil. man was that a slow shifting mutha.... LOL
 

·
Registered
Joined
·
400 Posts
I have never had a new T5. Old faithful gets a quart of Lucas ATF fix and then filled with some flavor of Mercon. It's one of the few snake oils I believe in.
 

·
Registered
Joined
·
1,102 Posts
The TR-3550/TKO are spec'd to use GM Synchomesh pn: 12345349. The Pennzoil Synchomesh is equal. In fact I've read that Pennzoil makes GM Synchomesh. Is what I read true? Can't say for sure, but I'm sure that GM doesn't refine there own lubricants. They establish their required specs and put it out to bid to be made under contract.

When you search the GM number, the Pennzoil comes up as meeting the GM spec. So....equal.
For the longest time, I ran regular ATF because it was the cheap alternative in my TR-3550. 2nd gear synchro "went out" when the transmission was fairly new. I didn't have the money to rebuild the transmission, so I got really good at double clutching on downshifts.

Fast forward 15 years, before an open track event, I decided to switch to Pennzoil Synchromesh just to have some new/better fluid. The first time I downshifted like normal I was surprised it didn't grind. Turns out, my trans didn't like ATF and I suffered with it for about 15 years until I decided to use the good stuff. For the last 10 years I've had the same synchromesh and it's been flawless.
 
  • Haha
Reactions: Nitrous SSC
1 - 20 of 34 Posts
Top