Ford Mustang Forums banner

T5 royal purple ATF vs synchromax???

25K views 26 replies 17 participants last post by  fox88  
#1 ·
I know ford says ATF but americanmuscle and Latemodel have both said synchromax is preferred. And yes ive searched but every thread has a different answer. So does anyone have any hard EVIDENCE on which one is better to use on a t5?
 
#3 ·
Just did this lol I did all kinds of research and #### gmsyncromax. I used first and then I had to take tenant out for other issues so I wanted to put better fluid I this time I almost put royal purple aft In There I could not find royal purple syncromax but it took some time I had to order it from orielys and wait for it but it was worth it tenant is a hell of a lot quieter and smoother then the gm #### and after you start researching transmissions and how they work you realize automatic cars use ATFbecause it has to be thin enough to go through the hydrolic system as where a manual does not have the problem so it can use a thicker oil witch will provide better lubricant and temps and quiet it down

But it's all up to you
 
#4 ·
i was doing a little more research and got this off the 4eyepride forum


"I know alot of people here are adamant about using ATF in the T5. Everyone has their own opinion so my question is... has anyone here actually ran Royal Purp in thier T5 and are they happy?

Here is a quote from Royal Purple:
Synchromax is recommended for manual transmissions that specify an automatic transmission fluid. It’s also ideal for 4×4 transfer cases and motorcycle gear boxes. Synchromax is fully compatible with all types of friction materials. It provides excellent corrosion and oxidation protection without affecting the soft metals commonly found in manual transmission synchronizers." - Jaz50
 
#10 ·
I put back in what the shop manual said. If the fluid from the factory is good enough for 10s of thousands of miles, it's good enough to refill the trans with it again for thousands of more miles.

Ahhhhh..... Such fond memories of being a Ford technician.

My 2 cents....
 
#11 ·
Synchromesh is not for T5s or any Borg Warner transmission. Common Dextron, III works great, when the transmission is built correctly and there are no problems with the transmission. Modern transmissions are designed for a specific viscosity fluid, when you change to a different viscosity fluid, the spin down time will be affected. So the transmission will not shift like it should at all times. I have built a lot of T5s, have raced fox body Mustang with T5s since 1989, I have been building T5s since 1989. I can shift T5s or most any other manual transmission faster than 98% of the people I have raced against. I have learned a lot about them over the years and tried all types of different things with them. Including running different fluids. I have never found a fluid that will allow a properly built T5 to be shifted any better than common Dextron III. I have tried a few different weights of engine oil, synthetic Dextron fluid, Including Amsoil and Royal Purple. I will say like I do about other Royal Purple products, I don't use that crap anymore for any reason., I have burnt up more parts using Royal Purple fluids than any other type of fluids. I have use the Royal Purple engine oil a lot, transmission fluid and gear oil, I have had problems with all of them. I have had good success with other synthetic fluids, but I still would not suggest a synthetic for a manual transmission, unless that transmission was designed for a give synthetic. Using a synthetic fluid that actually reduces friction, in a manual transmission, is like getting the friction surface of your manual transmission flywheel coated with a low friction coating.
I have also tried friction modifier upwards of three bottles. I have never seen a improvement of any kind. Something else to think about, is most manual transmissions were not designed to use synthetic fluids, the reason I point that out, is some friction is a good thing. If there was no friction, you would not get a synchronized transmission to shift at all. The blocker rings are friction rings, they basically act as small clutches. If the cone on a gear gets glazed, the blocker ring will not be able to produce enough friction to bring a gear to the speed of the output shaft. If the blocker does not get the gear you are trying to engage, to the speed of the output shaft very quickly, you will have a grinding problem. Using thinner or thicker fluids or lower friction fluids, does not help the blocker ring and cone do their job of getting a given gear to the speed of the output shaft quickly. The faster a blocker and cone can get a given gear to the speed of the output shaft at the point you are trying to shift gears, the faster you can shift.
All of this crap about this fluid is better than this fluid is all a bunch of BS. Use what the transmission was designed for, until somebody invents the miracle fluid, that actually works. Also, using to thick of fluids/higher viscosity fluids like gear oil in a T5, will cause the needle bearings to get burnt up pretty quickly. Because the thicker fluids will not be able to get to the needle bearings. The things that will help your T5 shift faster are better blocker rings or possibly a improved cone design on the gears.
 
#15 ·
From the manufacturer of the transmission -- page 2-1 -- http://www.tremec.com/anexos/TRSM-T5-0510-R1_173.pdf

"2-4. APPROVED LUBRICANT. Most T5
transmission models use Dexron“ II automatic
transmission fluid. Refer the vehicle owner’s manual
or service manual for lubricant specifications.
CAUTION
Do not mix different brands or types of transmission
lubricant. DO NOT USE GEAR OIL IN THE T5
TRANSMISSION SINCE THIS MAY DAMAGE THE
BLOCKING RING MATERIAL."

BTW - the all caps highlighting is the manufacturer's emphasis, not mine.
 
#16 ·
Most fluid wholesalers extoll the virtues of their products to develop a loyal following, even when any difference is meaningless.

Most people changing things to some fancy fluid will sense an advantage, feel, or sound improvement, even if there isn't one.

You can get 300k miles out of the friction wear parts of an engine with regular SAE oil if it is changed when it starts to get dirty, even if that is at 8k mile intervals. People who get 300k out of some fancy fluid will credit the fluid, even if it made no measurable difference.

I always use what the people who made the part say to use.
 
#17 ·
To Tom's point, I'd use a Dexron II or something that meets the equivalent specs. The synthetic versions tend to provide better performance on cold starts (especially if ambients are really chilly -- lower cold pour points than non-syn's) and if the fluid gets really hot (better resistance to viscosity break down at higher temps). I've changed mine twice in 40k and 15 years. Both times put in Mobil1's synth ATF for use in Dexron spec'd applications. Tranny works just as it always has. Which is to say smooth and quiet.
 
#18 ·
Great information here even if it is in the wrong section of the forum.

I sure like the way my T-56 Magnum shifts with the specified Dexron-III. Best advice is to use what the manufacturer recommends, they actually do know their products better than anyone else, and it's in their best interests to use a lube designed for the application.

Jay
 
#20 ·
I used Redline in my last Mustang. Was in there for 4 years and never an issue.

This time around, I thought I'd just try something different.

The T5 in my car was (supposedly) rebuilt just before I bought it (don't they all say that?) and when its hot, it doesn't miss a beat. When its cold? It wouldn't shift into 4th prob. 80% of the time, until it heated up. I thought I'd try something in it, just to see if it would make a diff. Being that I already did the Redline thing, I figured I'd give RP a try. Now, when its cold (going through the same driving pattern/route as I did before) only maybe once or twice has it not gone into gear when before it almost never did. The fluid I drained was pretty clean looking as well. Did it just need a change? Was it low? Did the RP simply just make it better? I'd have to put the stock fill back in to try it. But for me, it definitely made a nice diff. during those first couple miles. No question.

At some point, I'd like to switch to something stronger. Maybe an A5? If its new, I'll most likely use the factory recommended fill. If it works without issue, that's good enough for me.
 
#22 ·
ATF for the T5 because the blocker rings have a fiber lining that needs the cleaning properties of ATF. The fiber construction must be similar to the material in an automatic transmission.

Synchromax/Synchromesh is for TKO, 3550 etc. family of transmissions with the brass blocker rings.
 
#23 ·
I put Valvoline Synchromesh (from O'Reilly's) in my T5 and it shifts great. However, I have never tried ATF in this particular trans.
 
#25 ·
Part of what makes this challenging is that using an MTL fluid like Synchromesh in a T5 seems to make sense - after all, the T5 is a manual transmission. And most find that upon initially making the change, the tranny works just fine. I believe the problem with not using the ATF specified by Tremec, as mentioned by Hack above and in the manufacturer's footnote, is that an MTL fluid (like synchromesh) can damage the blocking ring material. And it doesn't happen all at once, but over time. So, if you've been running an MTL gear oil in your T5....it may come back to bite you later.