I live about 10 minutes away from the dealer and drove straight home normally (keeping it in S4 until I hit 45 mph). Since it would only shudder in D mode when the truck was fully warmed up, I didn’t want to try to test it out on the way home and see if it was cured.

I noticed immediately that it shifts harder, which is a good thing. Worth the $300? For me—yes. And that’s because I had a local shop that in all likelihood caused my issues in the first place. They serviced it twice, and (A) did not use Toyota OEM fluid, and (B) overfilled it by almost 3 quarts. If yours is slipping and you get the dreaded shudder, it might be worth it to flush & fill at a dealer as well.

I could have drained the trans at home and filled it to spec level with OEM fluid, but I don’t have the machine that cleans the transmission out. According to some, cleaning the buildup of film out of the torque converter is what helps it to stop slipping.

I’ll report back soon.