using what oil WAS in the sled has NO RELEVANCE (basically) to WHAT OIL you SHOULD BE USING.... Unless it is a castor "bean" oil, 99% of todays oils are MIXABLE!!! Which means, you could use ALMOST ANY oil on the market PROVIDING it MEETS OR EXCEEDS the MANUFACTURERS recommended specifications!!! If a MANUFACTURER tells you that you HAVE to run HIS OIL, HE MUST PROVIDE it to you FREE OF CHARGE!!!! (I think it was the magnusson/ferguson act??????) Its a LAW about 40 years old!!!! OIL COMPANIES DYE their oil to tell it apart and also to TRICK people into thinking that it is some special stuff.. There are only a HANDFUL of companies that MANUFACTURE and another handful of companies that REFINE and produce 2 stroke oils.... USING A SYNTHETIC oil will produce BETTER RESULTS ACROSS THE BOARD than ANY conventional oil... I spoke with a guy who puts 5000 miles a year on a snowmobile,,, every 2 years he sells it with 10,000 miles and buys another.... IT IS NOT feasible for him to buy so much SYNTHETIC oil, because he sells the sleds every TWO YEARS!!!!! IF YOU INTEND to put 5000 miles a year and sell it in TWO YEARS,,, DONT WASTE YOUR MONEY ON SYNTHETIC OILS!!!!! BUT,,,, If you want to keep you sled running LONGER and having FEWER oil related problems,,, LOOK INTO SYNTHETICS!!!!! SUCK OUT as much of that purple stuff as possible and fill it with synthetic oil!!!!! WHATEVER BRAND you feel comfortable with!!!! Gary Oles nosboy