Mini Cooper Forums - Mini Cooper Enthusiast Forums

Finally replaced the automatic transmission fluid on my 2002 Mini Cooper. It wasn't hard at all. I removed the battery, and battery tray. Underneath that was the fill plug. I unscrewed the transmission pan drain plug. I drained the oil while the car was off. 3 quarts of filthy oil came out (4 1/2 of transmission fluid should have came out). I added 4 1/2 quarts and 9 ounces of extremeoil. I drove it yesterday 23 miles without any problems. Today I put another 15 miles on it in stop and go traffic and no problems. The car drove normally. Prior to this after warming it up, it would start to act up while I was driving. The rpms would claim past 3K and it wouldn't go past 30mph. When I would come to a stop it would stay at 3k. Now it drops to 800-900rpms. Prior to doing any of this I also replaced my car battery. My charger told me the battery was no good. This on a mini can cause these problems. Another reason why your car may act this way is due to the rotational speed sensor being bad. You can buy a new one for around $48 shipped. I ordered one at https://www.aliexpress.com. I haven't installed it yet. I wanted to see if changing the transmission fluid and adding extremeoil would help first. So far it has. If your mini is acting like this before you junk it try changing the transmission fluid first before spending more money on it. Take it one step at a time. Oil then extremeoil then rotational speed sensor. Don't forget to have your battery tested. Total cost to get my car running smoothly so far $250 (that includes the cost of a new battery ($150) you might not need one). Hope this helps.