Should have updated with my personal experience a little while ago
Using TC-W3 1 oz/4 gallons during the winter fuel months. Smoother startups, quieter running, a little increase in MPG over 4-5 tankfuls. No harm done to spark plugs.
Have not used since summer fuel hit. Summer fuel by itself def makes a difference, but the engine is still not running quite as well as winter fuel + TC-W3.
Realize that this experience is on a PFI engine, not a DI engine, but it shouldn't hurt to try if you want. I used Walmart brand SuperTech (bought by the gallon, very cheap), and it worked well. Measuring & preparation with a funnel was the hardest part. I bought graduated beakers to help with that, I guess you can eyeball the amounts. The usual recommended ratio is more like 4 oz/20 gallons of fuel. I saw more results with 5 oz.
