Originally Posted By: HTSS_TR
Engine Flushes - DIY for about $10-15 once every 50k-100k miles is okay. Have it done at dealer for $100 or more is not.
Fuel-Injection Cleaning - Again, DIY (with Techron) for about $6-10 one a year is a good maintenance - Dealer price of $100+ is a rip off.
Oil Additives - Few are good at $5-10, if you know which one.
Gas savers - All of them are bad.
Fuel injection cleaning..... ON OLDER CARS that had 4 hole injectors or less,(roughly) CAN actually work,and work REALLY well. DEPENDING on the process and machine of course.
The envirolution system we used to have was AWESOME for previas, 22re, 4age, etc, all the older stuff. Did exaclly NOTHING for any of the newer style injectors. Neither does DR injector. Not sure about witchhunter.
Engine flushes...... might work on a car with hydraulic lifters. Like a Chev 350 or whatever.