Originally Posted by JARblue

I jack my car up perfectly level (within 0.01% slope, checked with a properly calibrated 4' digital level - I have to use different size jack stands to get it perfect in my garage) and refilling the transmission with exactly 3 quarts of fluid never causes overflow. You can't overfill it because the fluid will just pour out the fill plug when it's full. IMO it is better to pump enough fluid in there to make it overflow than to leave it short. However, if you can feel the fluid level when you stick your finger in the fill hole, it should be fine even if you only used 3 quarts.