Make sure you get the very best performance from your FOX® Shocks with the proper suspension fluid. Rigorous testing and engineering ensured they have the necessary viscosity to achieve optimal performance. So treat your FOX Shocks with the very best suspension oil: the XPS High Performance Suspension Fluid (For FOX Shocks). Thanks to its synthetic, fade-free formula for servicing FOX shocks, this suspension fluid is specifically formulated for high-demand or racing applications. Ultra-high VI shock oil.