Oil and Lubricants

Fork Oil and Lubricants Guide

Using the correct oil in your fork isn't optional — the wrong weight or volume directly changes how the damping circuit behaves. Fork oil does two separate jobs inside the fork, and getting either one wrong will make things worse, not better.

Bath Oil

Bath oil sits in the lower legs and lubricates the contact between bushings and stanchions. It reduces friction and prevents wear on the DU bushings. RockShox specifies 0W-30 in most forks (roughly 5–15ml per side depending on model). Fox uses 20wt FLOAT Fluid as bath oil in 34 and 36 forks. Maxima Plush and Motorex Fork Oil are popular third-party alternatives — they work fine as long as you match the viscosity to the manufacturer's spec.

Damper Fluid

Damper fluid fills the sealed cartridge and flows through the shim stack and compression/rebound circuits. This is where oil weight really matters. RockShox uses 3wt Maxima Plush Fluid in Charger dampers. Fox uses their own 20wt Gold in FIT and GRIP cartridges. Mixing brands at the correct weight is generally fine, but don't swap weights — running 5wt in a damper tuned for 3wt will make rebound sluggish and compression overdamped.

Grease and Assembly Lubricants

Suspension-specific grease goes on air spring seals, foam rings and dust wiper lips during reassembly. Slickoleum is the go-to — it's a low-friction synthetic grease that doesn't swell rubber seals. SRAM Butter is the OEM RockShox equivalent. Don't use standard bearing grease — it's too thick and can cause air spring binding.

How Often to Change

Bath oil should be changed every 50 hours or after particularly muddy rides. Damper fluid gets changed during a full rebuild, typically every 100–200 hours. The bath oil is a 10-minute job with basic tools — drain the old oil through the lower leg bolts, flush with fresh oil, and refill to the specified volume.