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, knowing how a shock absorber works is essential to understand how different oil weights affect them.
Why You Need Oil in Shock Absorbers
The shocks on RC cars work like those on your real-life car. They consist of a piston inside a tube filled with oil with a spring on the outside.
They cushion the effect of driving over rough terrain while 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.
What Do RC Shock Oil Weights Mean?
Like your car’s engine oil, shock oils have different weights, indicating the oil’s viscosity (thickness).
Modern engine oil is multi-grade, so you’ll see them rated with two numbers (i.e., 10W-30). The first number is their viscosity at low temperatures, and the second is their viscosity at high temperatures.
By contrast, RC shock absorber oil is single-weight, so they’ll only have one weight rating.
It’s made from silicone oil rather than fossil fuel or petroleum-based oils. 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.
There’s no direct comparison between CST and WT, so you must use a conversion table to compare the ratings.
Depending on the manufacturer, you may see the oil listed with either WT or CST.
CST to WT Comparison
| CST | WT |
| 100 | 10 |
| 150 | 15 |
| 200 | 20 |
| 250 – 300 | 25 |
| 350 | 30 |
| 400-450 | 35 |
| 500 | 40 |
| 550 – 600 | 45 |
| 650 | 50 |
| 700 – 740 | 55 |
| 800 | 60 |
| 850 | 65 |
| 900 | 70 |
| 950 | 75 |
| 1000 | 80 |
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 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 responds slower 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 Car | Front WT | Front CST | Rear WT | Rear CST |
| 1/10 scale touring cars, 4WD | 35 | 400 | 35 | 400 |
| 1/10 scale new model 4WD short course cars | 30 | 350 – 450 | 30 – 35 | 350 – 400 |
| 1/10 scale RC buggy 4WD | 30 | 350 – 450 | 30 – 35 | 300 – 400 |
| 1/10 scale RC buggies and short course 2WD | 30 | 300 – 350 | 25 – 30 | 250 – 300 |
| 1/8 scale buggies | 35 – 45 | 400 – 600 | 30 – 40 | 350 – 500 |
FAQ
How do you Choose the Right RC Car Shock Oil for Your Specific Car and Driving Style?
Choosing the right RC car shock oil depends on the weight and viscosity needed for the specific car and driving style. Factors such as the car’s weight, the type of suspension system, and the desired level of dampening can all affect the choice of shock oil.
Generally, lighter-weight shock oil is recommended for lighter cars or smoother tracks. In comparison, heavier shock oil is recommended for heavier cars or rougher courses.
It is important to consult the manufacturer’s recommendations and experiment with different shock oil weights to find the right one for your specific car and driving style.
How Often Should You Change the Shock Oil in Your RC car?
Generally, it is recommended to change the shock oil every few months or after every few uses.
Signs that the shock oil may need to be changed include:
- Decreased performance.
- Leaking or damage to the shocks.
- A change in the color or consistency of the oil.
Regular maintenance and oil changes can prolong the shock’s life and improve the RC car’s performance.
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 thick. Shocks can be damaged or broken on rough terrain if the wrong weight is used.
While you can use motor oil as an alternative in an emergency, it is best to stick to tried and tested oils for your RC shocks.
Can You Use Silicone Lube in RC Shocks?
Yes, silicone oils are a common type of shock oil used in RC cars. Silicone shock oil is known for its consistency and ability to maintain viscosity over a wide range of temperatures. This makes it a popular choice among RC enthusiasts.
Can You Mix Different Brands of Shock Oil?
Mixing different brands of shock oil is generally not recommended since different brands may have different chemical formulas. This could lead to unpredictable results.
It is usually best to stick with the same brand of shock oil for your RC car. Also use the same oil when changing or topping off the oil in your shocks.
If you need to change brands for some reason, cleaning out the shocks thoroughly before adding the new oil is recommended. Additionally, it is vital to ensure that the shock oil you choose is compatible with the materials used in your shocks, such as plastic or aluminum.
How Does Temperature Affect the Performance of RC Car’s Shock Oil?
Higher temperatures cause the oil to thin out, and lower temperatures cause the oil to become thicker. To account for these temperature changes, some drivers may use different shock oil weights or adjust their shock absorber setup.
For example, using lighter shock oil may help maintain optimal dampening in colder temperatures. In comparison, in hot temperatures, a slightly thicker shock oil may help to prevent the oil from thinning out too much.
Wrapping It Up
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 RC shock oils for flat, fast tracks. For rough terrain or large jumps, higher-weight oil would be the best choice.