The wrong grease can attack plastic gears, eat rubber seals, or wash out the moment things get wet. This is the short guide to matching grease to component, so you don't ruin a nylon spur trying to lubricate it.
"Grease" is a category, not a specification. Different greases have very different chemistry — base oil, thickener, additive package — and a grease that works perfectly on a steel-on-steel high-load contact will happily eat a plastic gear. One that's great for waterproofing will give up under high-RPM bearing load.
Across an RC build there are gears, bearings, diffs, O-rings and switches. Each one has different demands. The trick is matching the grease to the job rather than assuming one product handles everything.
Greases vary in three things: base oil viscosity (light vs. heavy), thickener type (lithium, silicone, PTFE, PFPE…) and additive package (EP, anti-wear, corrosion inhibitors, friction modifiers). Each combination is built for specific work. Match it to the part and you're done.
A lot of petroleum-based greases attack plastic — they cause swelling, softening, embrittlement or cracking. Often slowly enough that you don't notice until a gear lets go mid-run.
Use: Plastic Gear Grease (silicone-based, won't attack polymers)
Never use: petroleum-based greases on plastic gears
Same story for rubber — petroleum greases can swell or break down the compound. Silicone is the safe option.
Use: O-Ring Grease (silicone-based)
Where: shock O-rings, gearbox seals, anywhere rubber meets metal
Metal-on-metal under load needs an extreme-pressure (EP) grease. The thing keeping the metal apart is the additive package — MoS₂ (molybdenum disulfide), WS₂ (tungsten disulfide), copper particles, or similar.
Use: Copper Gear Grease, Moly Thrust Grease, Racing Grease Pro, or Rogue-X Heavy Duty depending on the load
Ceramic balls need low-friction lubrication — the wrong grease creates drag that defeats the point of upgrading to ceramics in the first place.
Use: Ceramic Grease (HBN nano-particle), or Heliox L15 PFPE oil if it's a really high-RPM application
A ball diff actually needs two different greases — one for the balls and rings, a different one for the thrust assembly:
They work as a pair. Thrust grease handles the load, ball grease handles the slip — together they keep the diff smooth and consistent.
These take silicone diff oil, not grease. See the diff oils page for viscosity selection.
Over-greasing is the most common mistake. Too much grease creates drag, attracts dust and debris, and slows things down. A thin, even coating is what you want — not a thick globby application.
When re-greasing, get the old grease off first. Old grease accumulates dust and worn metal particles that act as a mild abrasive. Clean with isopropyl alcohol, let it dry, then apply fresh grease.
Different bases (lithium, silicone, PTFE, PFPE) can be incompatible — they may separate, harden, or just lose performance. Stick with one type per application, and if you switch products, clean the component thoroughly first.
Racing: check after every weekend, reapply if it's looking thin or dirty. Bashing or casual use: check monthly, reapply seasonally. After heavy water or mud: clean and re-grease right away.
Quick workflow: