




⚙️ Shift smarter, drive smoother — don’t let your transmission miss out!
ZMAX 51-306 Transmission Formula is a 6 oz liquid additive designed to reduce carbon build-up, lubricate metal gears, and keep seals supple in automatic and manual transmissions. Engineered with PTFE, it improves shifting performance and extends transmission life, making it a must-have for proactive vehicle maintenance.














| ASIN | B00HEV2SK8 |
| Brand | ZMAX |
| Customer Reviews | 4.6 4.6 out of 5 stars (714) |
| Date First Available | 27 May 2015 |
| Item Weight | 226 g |
| Item model number | 51-306 |
| Manufacturer | ZMAX |
| Manufacturer Part Number | 51-306 |
| Product Dimensions | 7.62 x 7.62 x 13.97 cm; 226 g |
C**E
We have a 2014 GMC Acadia with around 109k miles. We purchased it used and when i got it i noticed the trans fluid had yet to be replaced. So i did a flush and the transmission improved 90%. However, 1 to 2 and 2 to 3 was a little hard shifting, not bad but i knew it shifted smoother than what it was doing. So i got ZMAX which ive used before in my oil, but never in a transmission. Needless to say it cleaned the shift points up perfectly. After driving around for about 30 min it was already shifting snoother. After my wife drove it back and forth to work for a couple days its now like new. Super happy with this product. This is not a product thats going to fix mechanical issues. But i believed my issue was just a varnish issue around the solenoid actuators where the oil had not been replaced. GM recommends every 40k miles on trans oil. So yeah if your having a little harder shifts then your used too. Get this and it will clean it up. You dont need to pull any oil out, just add the product and drive, its that simple. In about 1000 miles the product will fully soak in to all the metal and clean and lubricate varnish points. This product is not designed to fix worn out trans parts. So dont bother because it will leave a bad taste in your mouth. It simply soaks into the metal, allowing varnish or carbon to not adhere to the metal services. Look into Prolong or Bestline products if you need to treat a worn out transmission.
B**A
Best stuff on the market. Not cheap. But worth every penny
A**R
I have used Zmax for maddy years
M**L
I have a 2016 Taurus SHO with about 80k miles on it. I drive it hard and it does not disappoint but the shifting has always been hard since I bought it at about 30k miles. Not broken hard or a problem but I always wished it would be smoother especially on the downshifting when slowing down. I added this on a whim about a 100 miles after a transmission flush and am so glad I did. I noticed an immediate (within 20 miles) change in the shifting for the better. It is so much smoother and the downshifts are not nearly as abrupt, in fact I'd call them enjoyable. Best $17 I've spent on the car beyond a doubt. I highly recommend this product.
J**.
Great Product that works very well…I buy this stuff ALL THE TIME and put it into EVERYTHING w/ an engine… Thank you 🙏