Use light oil on bearings, gear grease on gears and diff joints, and a dedicated O-ring grease on seals. Using the right type for each part prevents damage.

Grease is thick and stays put on gears and pivots. Bearing oil is thin so bearings spin freely. Grease on a bearing would slow it down.

Re-lube after cleaning or when parts feel dry or notchy. Bearings, driveshafts and steering pivots benefit from regular attention.

Better not. Household products can swell plastics or attract dirt. RC-specific lubricants are made to be safe on the materials in your car.