I was able to get the footage that shows the Oil Tank sludge after using only 100LL for 100 hours. As i mentioned earlier. The footage was too large to put up here so check it out on Larson Adventures on youtube. I titled it::: ROTAX OIL TANK CLEANING. This was on a brand new rotax 912 engine. The first Oil change was at 25 hours and seemed very clean, The oil used was AeroShell Sport plus4, I used genuine Rotax filters on all of the listed oil changes. The Second Oil change was at another 25 hours (50 Total) and the 3rd oil change and tank inspection was at 50 hours (100 total hours).
I am going to switch to using mostly 91 octane Unleaded if possible. In my opinion a 25 hour oil change when using 100LL is better than at 50 hours. Oil is cheap and engines are expensive! I also like the way the oil tank is designed to allow the sludge and lead to float more to the bottom and not get sucked up into the engine.
