Thank-you. When I looked at Stihl Ultra specs on Stihl's UK website it says that Stihl Ultra is "ashless". Since Ultra is "ashless" it will not have the calcium deposits on the valves but as we all know it is an FB rated oil. Lots of carbon. So, I have been testing several "low ash" oils in my br800 and was just wondering about results in a 4-mix engine long-term. I have run VP at 40:1 and liked it. Other oils I like are Motorex Crosspower 2T 40:1, Amsoil Saber 50:1 (sorta clean, runs b+, good smell), Amsoil Dominator 40:1 (clean with very low smell, runs good when hot), and Maxima K2 50:1 (sorta clean runs great). My favorite is the Motorex Crosspower 2T because it runs great, runs clean, and to my nose smells the best. It's a full synthetic with a thicker viscosity than VP but not overly thick like HP2 and H1r. It's nice that VP is sold at Walmart. I've run oils that just take too long to heat up to their optimum run temp, and then oils like VP which is thinner and concerned me at 50:1. The viscosity was pretty low but I didn't notice high heat. Four oils that did not fare well were Maxima Super M (carbon), Maxima Super M Injector (high heat but super clean), Stihl Ultra (carbon), and Schaeffer's 710 tc-w3 36:1 (carbon). Stihl Ultra's flashpoint is very high and Stihl says (via email to me) if you're not using Ultra use a full-synthetic that is "equivalent" to Ultra. So... There is no fully synthetic "ashless" 2-stroke oil with a flashpoint anywhere close to the flashpoint of Stihl Ultra. So, thanks for sharing your experience.