Replacing the Fluid in a Self-Leveling Rear Suspension (SLS)

Oct 16, 2020


Welcome to Grafco Electric's comprehensive guide on replacing the fluid in a self-leveling rear suspension (SLS). If you own a vehicle equipped with an SLS system, it's crucial to understand the importance of regular fluid maintenance to ensure optimal performance and longevity of your suspension system.

Understanding Self-Leveling Rear Suspension

A self-leveling rear suspension, commonly known as SLS, is a sophisticated system designed to maintain a consistent ride height regardless of the vehicle's load or driving conditions. The SLS system utilizes hydraulic fluid to adjust the suspension's stiffness and height, ensuring a smooth and controlled ride.

The Importance of Fluid Replacement

Over time, the hydraulic fluid in the SLS system can deteriorate due to temperature changes, moisture ingress, and normal wear and tear. It is crucial to replace the fluid at regular intervals to prevent the suspension from malfunctioning, which can lead to a compromised ride quality, decreased stability, and potential damage to other suspension components.

Tools and Materials Needed

Before starting the fluid replacement process, gather the following tools and materials:

  • Jack and jack stands
  • Wrench set
  • Drain pan
  • Hydraulic fluid (specified for your vehicle's SLS system)
  • Clean cloth

Step-by-Step Guide to Fluid Replacement

Step 1: Prepare the Vehicle

Park your vehicle on a level surface and engage the parking brake. Ensure the vehicle is in a stable position and won't roll or move during the fluid replacement process.

Step 2: Locate the SLS Reservoir

The SLS reservoir is usually located in the trunk or under the rear seat, depending on the vehicle's make and model. Refer to your vehicle's owner manual or consult with a professional if you're unsure about the exact location.

Step 3: Lift the Vehicle

Using a jack and jack stands, safely lift the rear end of your vehicle. Ensure the vehicle is securely supported to prevent any accidents or damage during the fluid replacement process.

Step 4: Drain the Hydraulic Fluid

Place a drain pan beneath the SLS reservoir to catch the old hydraulic fluid. Locate the drain plug on the reservoir and carefully remove it to allow the fluid to drain fully. Ensure you have an adequate fluid-catching container, as the reservoir can contain a significant amount of fluid.

Step 5: Clean the Reservoir

After draining the old fluid, use a clean cloth to wipe the interior of the reservoir, ensuring it is free from any debris or contaminants. This step is essential to prevent any potential fluid contamination and maintain the system's proper functioning.

Step 6: Refill with New Fluid

Using a funnel, refill the reservoir with the specified hydraulic fluid recommended for your SLS system. Be mindful not to overfill the reservoir, as it can lead to pressure issues and potential system damage. Refer to the fluid level indicator or consult a professional for guidance during the filling process.

Step 7: Test and Adjust

After refilling the reservoir, lower the vehicle from the jack stands carefully. Start the engine and allow it to idle for a few minutes, giving the SLS system a chance to circulate the new fluid. Observe the suspension's behavior and check for any signs of leakage, abnormal noises, or uneven ride height. If necessary, make appropriate adjustments or seek professional assistance to ensure the system's optimal performance.


By following Grafco Electric's comprehensive guide, you now have the knowledge and understanding required to successfully replace the fluid in a self-leveling rear suspension (SLS). Regular maintenance of the SLS system will help extend its lifespan, enhance your vehicle's performance, and ensure a smooth and safe ride experience.

Remember, it is always recommended to consult your vehicle's owner manual or seek professional assistance if you have any concerns or lack the necessary experience to perform the fluid replacement process yourself. Taking proper care of your SLS system will reward you with a reliable and enjoyable driving experience for years to come.