B&M Racing “Synthetic Trick Shift ATF” (STS) update.

B&M Racing “Synthetic Trick Shift ATF” (STS) update.

Well all, I told you “time would tell” on how B&M STS ATF is working in the Honda SS Auto.

The news I’ve got is mixed.

On the positive side B&M STS has some pretty nice qualities:

- Lower transmission temperatures (up to 20 degrees lower)
- Slightly improved shift characteristics

On the negative side B&M STS has some unexpected qualities:

- The flash point of the ATF is 345 degrees F (All other “synthetics” are over 400 degrees) (Honda ATF is 380 degrees F)
- The MSDS sheet for the ATF indicates it is made out of “hydrotreated heavy paraffinic distillate” @ <60%.

The positive aspects of the fluid are a nice change over stock Honda ATF. The transmission shifts smoother, even when cold under normal summer / fall temperatures above 50 degrees F.

Additionally, the operating temperature of the transmission is significantly lowered. This has a very positive effect on the life of the fluid.

On the down side, the B&M STS ATF is clearly not a true non-petroleum synthetic ATF as should e expected whenever the word “synthetic” is used. The fact that it has a flashpoint of 345 degrees in laboratory test indicates that the fluid is a conventional ATF. My initially suspicions were proven when I was able to obtain the Material Data Safety Sheet (MSDS) for the B&M STS ATF from B&M Racing.

I think it’s really important to take a second and drum this aforementioned point home:

B&M is marketing their “Synthetic Trick Shift ATF” as a synthetic product due to a legal loophole. The fluid is actually NOT a non-petroleum based synthetsized product. Until about the time Castrol Syntec came on the market, synthetic oils (lubricants) were called synthetics because they were completely created using chemical reactions to produce oils with the desired chemical properties. This is different than the process of refining petroleum in order to return a specific weight oil. The primary difference is that no matter how much you refine petroleum, you generally end up with a certain amount of the impurities found in the original substance. Generally, the process of removing paraffin (wax) from petroleum is known as “hydrotreating” or “hydrocracking.” The process of refining a petroleum product can technically be considered “synthesizing” a new product and allows marketing departments to call a petroleum based product a “synthetic” product.

The problem with petroleum based products is that they tend to be much more volatile than true synthetic products. What does that really mean? It means that non-synthetic products tend to evaporate into thicker lubricants which then cease to properly function in your transmission. Furthermore, as they evaporate they breakdown and coat your transmission with varnish, gum, or sludge.

Interestingly, the lab tests on an unused sample of Honda ATF indicated that its flashpoint is 380 degrees F, a full 35 degrees F higher than the B&M STS ATF. The viscosity index was also slightly better, but otherwise the fluids were very similar.

The real question is: What ATF should you use in your 5th Gen Honda Prelude?

Well, if you car is under warranty, you need to stick with an ATF that is RED in color. Honda will never know if you don’t have Honda ATF, but I’m sure some of you will want to be careful and use it.

So far, I’ve found that mixing B&M STS and Mobil 1 ATF works very well. The blend seems to provide a fluid that has both the shift characteristics that I’m looking for and the cold start characteristics that I require as well. I’m in the process of sending the mixed fluid out to the lab to find out if its combined chemical properties are what I’m looking for.

A follow on question is: Is B&M STS ATF worth paying the $8.00 a QT list price?

No. I’d have to say that installing an ATF cooler and using Honda ATF is probably a better choice. Over the life of your vehicle the $40.00 for a B&M tranny cooler is going to be cheaper and almost as effective as using B&M STS ATF.

It is possible that B&M’s STS ATF has a better additive package than the Honda ATF, but I’ve got no way to verify it. The chemical break downs listed in my lab tests only cover typical concerns such a TAN, trace minerals, and insolubles. Usually, ATF additive packages are compared against how well the additive prevents acid build created by worn out ATF. Both fluids seem to have comparable additive packages in the laboratory tests.

Personally, I’m much more likely to mix the Honda ATF with Mobil 1 or AMSOIL ATF's, as well as use a transmission cooler. I’ve found that using a 50-50 mixture of conventional ATF and synthetic ATF improves the shift quality dramatically, without adversely effecting the transmission while lowering the pour point of the ATF mixture. (The last part means that the fluid will shift better at colder temperatures.)

It is important to note that Honda requires fluids with low silicon to protect the seals. The B&M fluid meets this requirement at 12 ppm vs. Honda ATF being 4 ppm. The difference is somewhat insignificant and should really have no impact on the transmission’s seals.
B&M STS ATF does improve operating temperature (by lowering it) and shift quality over Honda ATF. However, if you are using Honda ATF or B&M STS you still should consider installing a transmission cooler.

I have contacted B&M Racing, I’ll post that message I send them as a reply to this one. I’ve not heard back from them, but will post that response when (if) I do.

-Gerhard