Take one look at this photo and you should realize the importance of rebuilding your shocks. This is some of the shock oil from our 2006 Arctic Cat Crossfire 7 after a very brutal 2000 miles. Full of contaminants and water. Corrosion had already started to attack the inner components. Bottom line, even if your sled was brand new this year, do yourself a favor and get the contaminated oil out of there. The first rebuild is most important, some serious riders will do it after the first 500 miles just to get rid of the break-in residue. At a minimum, one should be doing this at the end of every season. If not, be prepared to deal with additional parts replacement due to the corrosion.