2.5wt RSF Racing Fork / Shock / Suspension Fluid Oil 1 Litre. SILKOLENE - Fork & Suspension Fluid Range High VI index formulation. Combined with low friction synthetic additives ensuring smooth and assured damping on all terrain. Grades can be mixed. The FUCHS Silkolene RSF range (formerly known as Pro RSF) has replaced the standard Fork oil Counterparts. Our premium high performance RSF range, available in (2.5, 5, 7.5, 10 & 15 W) is a race/road/track proven suspension fluid already in use and chosen by many of todays market leading suspension manufacturers and currently already used as original equipment in many of todays modern motorcycles.