I broke my clutch hydraulic line within two months of getting my '99 300EXC. I replaced it with a much more durable steel braided one from Enduro Engineering. At that time I asked the dealer what to use for fluid and they suggested using common mineral oil, available at any drug store for about a dollar a quart, which is a lifetimes worth. As maintenance, I have replaced the fluid twice in the 3 years since then. I have had absolutely no problems with the hydraulic system in those 3 years.