The FOX 4WT Suspension Oil is a high-performance synthetic fluid developed in collaboration with Motorex. It features advanced 3D Response Technology, which uses a unique molecular structure to dissipate impact forces across a grid-like network rather than a traditional linear path. This results in a significant reduction in stiction and a more refined, predictable damping feel.
Notably, FOX has recently transitioned its oil lineup, and the 4WT formula now officially replaces the discontinued 5WT PTFE-infused oil for all modern damper applications.
3D Response Technology: A specialized molecular composition that improves air separation and provides a more consistent damping response under high-stress loads.
Reduced Breakaway Force: Engineered to minimize the "stick-slip" effect, allowing the fork or shock to begin moving more easily over small bumps.
Superior Thermal Stability: Maintains its 4WT viscosity across a broader temperature range, preventing the suspension from feeling "slow" in the cold or "blown out" in the heat.
Anti-Foam & Anti-Corrosion: Advanced additives prevent air bubbles from forming in the oil (cavitation) and protect internal metal surfaces and seals from premature wear.
Large 1L Volume: The 1-liter bottle is the most cost-effective option for home mechanics or shops, providing enough fluid for multiple full-service intervals.
| Feature | Specification |
| Viscosity | 4WT (Replaces legacy 5WT PTFE) |
| Volume | 1 Liter (approx. 34 fl oz) |
| Compatibility | GRIP, GRIP2, GRIP X/X2/SL, and Rail dampers |
| Shock Support | FOX DHX2 (2021+) and Float X2 (2021+) |
| Base | High-performance Synthetic |
Modern FOX Fork Owners: This is the mandatory factory-spec oil for all MY25 and newer forks equipped with the GRIP X, GRIP X2, or GRIP SL dampers.
Legacy GRIP/GRIP2 Users: If you previously used the "Orange" 5WT PTFE oil, this 4WT is the official replacement. It is fully compatible and can even be mixed with remaining 5WT PTFE oil during a lower-leg service without issues.
Rear Shock Servicing: Essential for the inner damper service of the Float X2 and DHX2 (2021 models and newer).
1.5WT Damper Requirements: If you are servicing a Transfer seatpost or a specific racing damper tuned for 1.5WT Red Line oil, this 4WT will be too thick and will significantly slow down your rebound and compression.
Lubrication Bath: For the "air side" or lower legs of many forks, FOX specifically calls for 20WT Gold Bath Oil. Using 4WT as a bath oil may not provide enough film strength for the bushings in some models.
Older Open-Bath Forks: Older FOX forks designed for heavier 7wt or 10wt oils will not have enough damping resistance with this lighter 4wt fluid.
If you are transitioning your fork from the old 5WT PTFE (Teflon) oil to this new 4WT, you do not need to perform a chemical flush of the damper. Simply drain the old fluid as normal and refill with 4WT. However, always ensure you check the 2025 Bath Oil Volume Chart from FOX, as many newer forks use a combination of 4WT in the damper side and 20WT Gold in the air side for optimal lubrication.
