RC Shock Oil Weight Guide

Your RC car’s shock absorbers take a hammering running over rough terrain. Changing the weight of the oil in your shocks improves performance and can extend their lifespan as well. 

The trick is to know what oil weight to put in your RC car’s shocks. 

Choosing the right oil can help you corner better and land easier after jumps. However, the wrong oil will increase your car’s response time, making it feel sluggish. 

This article will give an overview of oil weights and provide recommendations based on the type of RC car.

First, it’s essential to know how a shock absorber works to better understand how different weights of oil affect them. 


How Do Shock Absorbers Work?

The shocks on RC cars work similarly to those on real-life vehicles. They consist of a piston inside a tube filled with oil with a spring on the outside. 

This provides a dampening effect over rough terrain or jumps while also stabilizing the car when cornering.

When the RC car drives over bumps, the shock absorber is compressed, causing the piston to travel up to the tube’s head. Without enough dampening in either the tube or the spring, the piston slams into the head of the tube. 

This is called ‘bottoming out,’ and it can cause severe damage to your car’s suspension.

So what role does the oil play in the shock? 

The oil inside the tube helps lubricate the piston sliding inside the tube while providing additional dampening to the shock absorber. As the RC shock absorber is compressed, the piston, in turn, compresses the oil inside the tube.

This compression slows down the movement of the piston in the tube, preventing it from bottoming out. 

Traxxas 60WT RC shock oil

What Do RC Shock Oil Weights Mean?

Similar to your car’s engine oil, shock oils come with different weights, which indicate the viscosity (thickness) of the oil. 

Modern engine oil is multi-grade, which is why you’ll see them rated with two numbers (i.e., 10W-30). The first number is their viscosity at low temperatures, and the second number is their viscosity at high temperatures. 

RC shock absorber oil is a single-weight oil, so they’ll only have one weight rating. It’s made from silicone oil rather than fossil fuel oil or petroleum-based oils, so you should only use an oil designed for RC cars in your shock absorbers.

The weight or WT rating of the oil is generally shown in multiples of 10 or 5. 

For example, 10WT oil is very thin silicone oil, while 35WT oil is thicker. Each weight gives different performance characteristics to the shocks.

Thicker oil provides better lubrication and superior shock dampening to thin oil but is more sluggish in its response. By contrast, thinner oil does not coat the components as thickly and is less efficient as a lubricant. However, it has a much faster rebound rate and recovery after compression.

However, weight is not the only unit used to show the viscosity of the RC shock oil. 

Another standard called Centistokes, or CST, is another commonly used measure of oil viscosity. Similar to the WT rating, the viscosity of the oil increases with a higher CST rating.

CST and WT are not comparable, so you need to use a conversion table to compare the two ratings.

Depending on the manufacturer, you may see the oil listed with either WT or CST. 

CST to WT Comparison

CSTWT
10010
15015
20020
250 – 30025
35030
400-45035
50040
550 – 60045
65050
700 – 74055
80060
85065
90070
95075
100080

What Shock Oil Weight Should You Use In Your RC Car?

It’s common for front and rear shocks to use different oil weights to impart different characteristics to the front and rear suspension.

The best shock oil weight depends on your car’s weight, whether the vehicle is 2WD or 4WD, and the type of terrain you drive on. 

Generally, the heavier the RC car, the higher the WT or CST oil is required for the shock absorbers. 

Heavier oil will give better lubrication and better traction on rough terrain. The steering is slower to respond with thicker weight oil, particularly when cornering.

Lighter weight oil is suitable for lightweight or fast cars on smooth terrain. 

The steering is more responsive when cornering. However, if your oil weight is too light, the steering may be a little twitchy, causing spinouts in corners.

The following table is a guideline for shock oils typically used in some standard RC Cars. 

These are basic guidelines, and you can experiment with less or more viscous oils to fine-tune your ride!

General RC Shock Oil Weight Recommendations

RC CarFront WTFront CSTRear WTRear CST
1/10 scale touring cars, 4WD3540035400
1/10 scale new model 4WD short course cars30350 – 45030 – 35350 – 400
1/10 scale RC buggy 4WD30350 – 45030 – 35300 – 400
1/10 scale RC buggies and short course 2WD30300 – 35025 – 30250 – 300
1/8 scale buggies35 – 45400 – 60030 – 40350 – 500

Can Motor Oil Be Used In RC Car Shocks?

Some RC car drivers use standard motor oils in their RC shock absorbers. However, this is not recommended because the motor oil weight rating is not the same as the silicone oil weight rating for oils designed for RC cars.

Petroleum-based oil can also negatively affect the shocks and the components if the oil is too thin or too thick. Shocks can be damaged or broken on rough terrain if the wrong weight is used.

While motor oil can be used as an alternative in an emergency, it is best to stick to tried and tested oils for your RC shocks.

Conclusion

As you gain experience with your RC car and how it handles different terrain, you can begin to tweak its performance by adjusting the oil weight in the shocks.

Always make changes in small increments and thoroughly test each terrain type, especially before trying large jumps with the RC car.

Generally, as a rule-of-thumb, you would use lower weight oils for flat, fast tracks in your shocks, and for rough terrain or large jumps, higher weight oil would be the best choice.

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