Didn't think I would have anything to add to 20 pages of oil discussion but... I called a couple lawn mower shops to find Opti 2. Neither had it but the second shop does not recommend it. He found over the years that if an engine had used it in the past than it always needed to use it. He had several engine seizures when people had switched. I asked then if it was good for our engines. He said it was probably great, but he won't carry it because he doesn't want his customers to switch back and forth. He said to tell you guys "if you use it, keep using it" So, it sounds just fine to me. Great results, great price per gallon, why switch back to anything else. On a random note - what color is the fuel after mixed? *Note - I am just saying what he said. His whole life he has been repairing lawn mowers. He was speaking from experience. Could have been a million other issues that we could all argue about here. It's not like he was knocking the product, he just won't carry it in his store because of issues he has had with engines that used it in the past.