Product guide

How do I choose diff oil for an RC car?

By the Rhodex RC Line product team (IGNIS Overseas Ltd, Isleworth, UK). Claims reviewed by IGNIS Product & Compliance on 14 Nov 2026. Last updated: 14 November 2026.

Short answer. Start from the diff oil weight in your car's manual or setup sheet. Rhodex RC Line Silicone Differential Oil is graded in cSt: thicker oil makes the diff act more like a spool (more drive, less turn-in); thinner oil lets it differentiate more. Change one diff at a time.

Key facts

  • Product: Rhodex RC Line Silicone Differential Oil
  • What it is: Silicone differential oil, sold by viscosity grade (cSt)
  • Made for: RC gear differentials
  • Not for: Shocks; ball differentials (use Ball Diff Grease)
  • Who makes it: Rhodex is a brand of IGNIS Overseas Ltd, Isleworth, UK

How to do it

  1. Check the manual's starting weight.
  2. Drain and clean the diff.
  3. Fill to the level the manual shows.
  4. Reassemble; check for leaks.
  5. Test; adjust one diff at a time.

When to choose something else

  • Ball diffs: Ball Diff Grease.
  • Three-weight comparison: Diff Oil Tuning Set.

Common mistakes

  • Over-filling, which pushes oil past seals.
  • Changing front, centre and rear together.

FAQ

Which end first? Many tuners start with the centre diff on 4WD cars.

Sources

Your equipment maker's manual

Get the Range

Buy Rhodex on Lubricants Hub.

The full Rhodex line is stocked at Lubricants Hub — every viscosity, every grease, every kit. UK fulfilment, international shipping.