Every 30k to 40k miles in a high HP/TQ vehicle.

Every 40k to 60k miles in a stock OEM vehicle.

Every 80k to 100k miles.

If the first fluid change is at 100k miles, plan on changing the Valve Body with solenoids around 130k to 150k miles.

If the fluid has never been changed on 130k miles or higher then replace the Valve Body with solenoids plus the bridge seal and 4 round sleeves.

Once you are making 550HP and up

Once you are making 550HP and up