“My very high-mileage Volvo has so-called “lifetime” transmission fluid. It holds a little more than 7 liters. I drained and refilled the system three times (usually a little more than 3 liters replaced each time.) First time it came out nearly black, after that lighter and lighter carmel color (the new fluid is red.) One last time with one difference, I added a bottle of TransTune and drove the car for about a week. The same carmel color fluid drained out. After putting in the new red fluid, I removed the small drain screw to adjust the fluid level–(Volvo doesn’t make it easy. You are supposed to let the fluid stream out until it begins to come out in individual drops, then you put the screw back in and the level is set.) Amazing that the fluid was bright red like I poured it straight from the transmission fluid bottle. Without changing the transmission filter, the TransTune cleaned out the last of the old transmission fluid in a car with very high mileage. Shifting is back to being smooth too! I recommend this product to anyone with a higher mileage car for the transmission and to everyone for maintaining their power steering fluid pump.”