You're running on your favorite layout cutting your best lap times when
suddenly and without warning your car begins to slow and squeal." What's
going on here", you say to yourself. Quite possibly,you may be
experiencing a lack of lubrication. The HO unit is a finely honed piece
of miniature electrics which requires periodic lubing.
Oiling your car at the proper intervals will fend off heat and friction which is detrimental to going fast. When speaking of oiling and lubing, we are looking at axles, armature shafts,bearings and gears. Most manufacturers blow out diagrams will point you in the right direction as to which areas need attention. Begin by oiling the motor shaft with a micro drop of lightweight oil such as 3 in 1 or other lightweight or synthetic oil. Oil every hour of operation or sooner if the car begins to slow down, "whirr" or "squeak". Oil can be applied using one of the recommended special dispensers available at hobbyshops,electronics stores or through mail order. I built a hybrid oil applicator from an old BSRT micro oiler cap and needle tip "superglued to a B-D syringe body. This combination works well, holds 3 cc's of oil, doesn't leak, is durable and places the precise amount of oil where the chassis needs it.
Avoid over oiling. Avoid getting oil on pickup shoes as this attracts dust. Avoid getting oil on commutators or brushes as this is " instant death" to your car. Some people have had great success using lubriplate or white lithium grease (available at gunshops or automotive parts stores) on stock and custom gears. Even polymer gears can benefit from lubrication. This can be applied using a pin and aids in preventing high heat friction, gear mesh problems and premature wear and "tooth" chipping (assuming your gears are set up properly to begin with!)
Try it and hear and feel the difference.