I had my tank steam cleaned after truck sat dormant for more than 10 years. I was amazed at the difference it made in the way the truck started and ran. I had previously drained and refilled the tank thinking that good enough but the stale fuel varnish was worse than I would have thought. I have the stock behind the seat tank and there are no baffles in it. I am a believer in the process. Again, The shop used steam only on mine.