Piston Slap: Zoom Zoom, Mesh!

Anonymous writes:

I love this column, great advice every time. That’s why I decided to ask for your opinion on something that’s been bothering me for a while. I have a ’07 Mazda3 hatchback with a 5-speed manual. Currently I’ve crested 23,000 miles and the car is still under warranty.

Ever since I bought the car (brand new), the shifter has been a bit notchy going from 1st to 2nd. It could also be smoother from 3rd to 2nd. Another thing that bugs me is that during our cold Chicago winters, until the car/transmission warms up, the shifter is very mushy and stiff. Otherwise, the car is a blast to drive.

So I’ve read a bit about GM’s Synchromesh Fluid and from what I hear, it does wonders and it should fix my problems if I were to swap my transmission fluid. Now here are my questions regarding this:

1) In your opinion, do you think I would really feel the difference: much smoother shifts all around and easy shifting in cold weather? Or is it just a placebo effect?

2) My Mazda dealer wants almost $200 for the fluid swap with their own fluid. For various reasons I can’t do it on my own and I don’t feel like trusting a 3rd party mechanic. The dealer has been fairly trustworthy so far. Do you think it’s a fair price? Would it make more sense to bring my own fluid, such as the Pennzoil Synchromesh sold by Autozone?

3) Should I be concerned that the dealer might use regular fluid instead of Synchromesh? I believe they are honest but you never know and the customer is not allowed in the shop anyway…

I would really appreciate a good suggestion for this dilemma.

Sajeev Replies:

Question 1: to reiterate, I noticed a significant improvement in shift quality with a fluid change to GM synchromesh. Then I noticed a minor improvement with said fluid swap on another vehicle. Either way, I think it is a win. And you don’t have to buy the bottle with GM’s Mark of Excellence, but theirs seems like a good value. The last time I priced checked, of course.

Question 2: That is a somewhat-fair price, but now’s the time to trust a third party mechanic. Look for one with a clean shop, loyal customers to a veteran shop owner and a computer with access to on-line service information systems like ALLDATA.

Question 3: There’s a good chance the dealer will use your fluid, because you (a smart consumer) only pays for labor. Then again, they may flat-out refuse to use non-Mazda fluids in your car. If so, refer to my answer to the previous question.

(Send your queries to mehta@ttac.com)