So I'm a college student with a 2008 Toyota Matrix with 64,500 miles clocked on the odometer. Recently, I realized that the 4 speed automatic transmission shifted a bit roughly at colder temps. I live in Ohio and the vehicle is parked outside so it routinely stays in below freezing temps for extended periods of time.
After some research, it seemed as though changing the auto trans oil would be a relatively simple solution to provide smoother shifts. After all, I've changed the motor oil on the vehicle numerous times. So I purchased 4 quarts of Toyota T-IV Trans fluid from the local dealer and proceeded with the drain and fill. Altogether, I probably drained between 3.7 to 3.8 quarts from the auto transmission. However, once I added the fluid, the dipstick reads full after adding 3.4 quarts. Is the vehicle good to go? Or should I add 0.3-0.4 more quarts of trans fluid to exactly replace the fluid that I drained?
The dipstick always reads the same level regardless of whether or not the fluid is warm or cold. Therefore, I'm not relatively confident in the accuracy of the dipstick oil reading (which stays at the 'full level' whether or not the vehicle is warm or cold).
I drove the vehicle briefly afterward and it shifts smoothly and adequately. I'm not sure how to proceed at this point.