[Old Thomas]

All gas contains cleaners to keep the fuel injection system clean. I never add anything or do anything to the FI system unless there is a problem, which has never happened since the fuel pump on my previously owned S10 failed 15 years ago. I change the trans fluid and filter at 100k miles and every 50k or so after that (OEM says 150k). I have a lift and I do it myself. If yours smells and looks ok, look at your owner’s manual for the maintenance interval. I recently changed the fluid in my F150 trans at 100k miles, it looked and smelled new and there was almost no debris in the pan. When you service the trans spend the money on OEM fluid. Slight variations can make a big difference.