The blue grease from 1upRacing is specially designed for all types of O-rings. When servicing the diff or shock absorber, simply coat the O-rings with the blue grease and reinstall them. This protects the O-ring from silicone oil, which would otherwise cause it to swell. A swollen O-ring creates greater friction and thus greater resistance on the diff outdrive or shock absorber piston rod. With the ‘Blue O-Ring Grease’ from 1upRacing, you can protect your O-rings and improve the performance of your RC car.