I bought a new assault 155 about a month ago. I had to leave for work for 2 weeks and told my brother if we got snow, live in WI, that he could ride the sled. Just got home for christmas and noticed that the oil res was completly full and asked him if he had to fill it at all since he had been riding it. He said it was only half full from dealer, he ran it down to about a 1/4 full then filled it with redline oil. I know that you are not supposed to mix oils, but dont know how serious this is. I did run it for about an hour or two before noticing this and then havent rode it since. Think i need to drain the oil out and go back to straight polaris oil? Any help would be greatly appreciated. Thanks guys!