What fluid in a T5Z?

[montegoman351]

I have the opportunity to get a T5Z with about 100 miles on it, the guy bought the car, took out the T5Z, and is going to an auto instead. Well, long story short, I was wondering what type of fluid you guys run in your T5's.

I know Mercon is the standard, but what about Royal Purple SyncroMax?

Thanks again.

 

[BlownFiveLiter]

Use standard ATF, not synthetic. The synthetic lube actually promotes premature wear of the synchros.

 

[Mustang5L5]

What he said

 

[Deleted member 87397]

How is it that the synthetic stuff which is supposed to be better for your synchros cause premature wear. I'm not doubting, but do we have anything to back this up or an explanation as to why it causes premature wear?

 

[Mustang5L5]

How is it that the synthetic stuff which is supposed to be better for your synchros cause premature wear. I'm not doubting, but do we have anything to back this up or an explanation as to why it causes premature wear?

Because it's more slippery.

So when you shift, it takes longer for your synchros to grab and match the speed of the gear due to the slickness. Because of that. the wear rate is increased.

Non-syn isn't as slick, so it grabs the synchro instantly. Since the t-5 is a great shifting trans in general, this really isn't an issue.

Use non-syn as it was designed for.



Tremec actually has a TSB on the 3650 to change the fill from synthetic to non-synthetic for this reason. The 2nd gear synchro doesn't grab that well as a design flaw so a band-aid is to run fluid that will allow it to "grab" better. It really is a cheap band-aid.

Synthetic fluids aren't always "better" so to speak.

 

[fiveohlxhatch]

I run regular ATF in my T5Z and it shifts flawlessly.

 

[SPEEDYLIFSAVR]

I run Mobil one , but sounds like I'll be switching . I was not aware of the synchro issue but sounds feasable .

 

[montegoman351]

Thanks guys, Mercon it is!

 

[Deleted member 87397]

Excellent 5L5. Thanks for the explanation.

 

[Foxfan88]

i always run the cheapest dex/mer 3 ATF works great!

 

[93gtmustang]

I've talked to Tremec tech about this.
I've had the Royal Purple ATF synthetic in my T-5z for 1500 miles.They said that I would have noticed some problems by now if it wasn't working correctly. But this product has never been tested by them, so he reccommended draining it to be on the safe side. Most companies won't tell Tremec what type of additives are used, so that is why they only test the major ones. And for synthetics, Mobil One is reccommended and has been tested. Other synthetics can actually be too slick and cause slipping.
I was told that regular Dexron III works the best.
For my car application, which is a street legal car, mainly used for drag racing, he reccommended GM Synchromesh. You can get it in the Pennzoil brand in the gear oil section at most parts stores.
I went with the regular old Dexron III in the Valvoline brand.