Atf vs Synchromesh

[Tim W.]

My show truck has a Tremec TKX 5 speed transmission

The problem is there is so much misinformation out there about what fluid to use. I dont think Tremec even knows .

I was experiencing a minor TKX issue (non fluid related). I was running Amsoil signature ATF fluid after break in w no issues. I drained the fluid to check for metal.

I refilled w Penzoil Synchromesh bc that's what the store had and I saw it was an approved fluid from a google search. However, I was later told by a transmission shop Tremec no longer recommendeds SM in the TKX.

Heres the twist. I called Tremec and spoke w a trans tech. He said, no Sm, only a high quality ATF such as their brand or Mobile 1.

Now for the kicker. The same company emailed my buddy bc he had the same question. They sent him a list of Approved fluids

" We recommend TREMEC HP-MTF, GM Synchromesh™ or Mobil 1 Synthetic ATF". Wth....

Should i listen to the Guy I talked to or the email? I did buy a case of their brand fluid just to be safe. But until it comes I don't wana destroy my 3k transmission.

Also, if I drained the SM and added ATF will the residual SM clash with the ATF?

 

[JavierH19]

Never take what representative have to say as the most correct thing. They almost never know what they're saying. In summary GM used thin atf for fuel economy but the tremec documentation which is to be trusted over everything else says to use gl4 75w-85 which is their hp mtf. They know the thin stuff is fine for the most part but if it was the best they'd say to use thin atf instead. It's why it says what it says in the first bullet point under benefits for the thicker fluid. Protects more under high temps which would also be high loads.

I'd leave SM in there it's good to use. And no SM won't clash with atf in any way.

Lubrication Specifications
For all TKX 5-speed models, TREMEC recommends TREMEC High Performance Manual Transmission Fluid
(HP-MTF™), Dexron-III, GM Synchromesh™, Mobil 1 Synthetic ATF, or Pennzoil® Synchromesh. Fluid capacity
is 2.7 quart / 2.6 liter.

 

[Pablo]

Wow they recommend quite the range from 7 cSt to 12+

If you live really cold, maybe a ~7 cSt would be OK

I recommend the middle: https://www.amsoil.com/p/amsoil-5w-30-manual-synchromesh-transmission-fluid-mtf/?zo=515729

 

[Tim W.]

Never take what representative have to say as the most correct thing. They almost never know what they're saying. In summary GM used thin atf for fuel economy but the tremec documentation which is to be trusted over everything else says to use gl4 75w-85 which is their hp mtf. They know the thin stuff is fine for the most part but if it was the best they'd say to use thin atf instead. It's why it says what it says in the first bullet point under benefits for the thicker fluid. Protects more under high temps which would also be high loads.

I'd leave SM in there it's good to use. And no SM won't clash with atf in any way.

Lubrication Specifications
For all TKX 5-speed models, TREMEC recommends TREMEC High Performance Manual Transmission Fluid
(HP-MTF™), Dexron-III, GM Synchromesh™, Mobil 1 Synthetic ATF, or Pennzoil® Synchromesh. Fluid capacity
is 2.7 quart / 2.6 liter.


View attachment 303201

Thanks for the explanation. Ill run what I have until the the Tremec stuff comes.

 

[Tim W.]

Wow they recommend quite the range from 7 cSt to 12+

If you live really cold, maybe a ~7 cSt would be OK

I recommend the middle: https://www.amsoil.com/p/amsoil-5w-30-manual-synchromesh-transmission-fluid-mtf/?zo=515729

Yea Tremec's recommendations are all over the place. I orderd their stuff. Im sure their stuff is rebranded oil, with a steaper price tag.

Im wondering if Mobil 1 makes their oil since they actually mention M1 by name.... But, I guess they mentioned Penzoil too, so who knows.

live in south Texas. So, yes It "can" get cold, but its usaully a mild winter.

 

[Tim W.]

It could be in my head but I took my truck for a stroll with the Penzoil Synchromesh fluid in my TKX and it shifts so much better. Its way less "notchy".

I did a "google search" which im not sure how much I trust it, but it said Penzoil SM is compatible with the TKX's sintered bronze and carbon synchronizers.