AMSOIL Shock Therapy #5 Light Suspension Fluid

AMSOIL Shock Therapy® #5 Light Suspension Fluid

Developed for those who demand top performance from their suspension systems. Ideal for circle-track racing applications, cars, trucks, snowmobiles, ATVs, UTVs and motorcycles. To cross-reference against your current product, visit shock fluid cross reference.

See the product data sheet for AMSOIL Shock Therapy® #5 Light Suspension Fluid details.

CONTROLS DAMPING & REBOUNDS

• Formulated to make suspension systems more predictable.
• High-viscosity-index base oils effectively maintain viscosity for maximum performance.
• Anti-foam agents reduce aeration and foam to promote predictable suspension feel.

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REDUCES FRICTION & WEAR

• Contains friction modifiers to reduce energy loss due to friction for optimum efficiency.
• Formulated with anti-wear agents that protect shocks and forks from premature wear for long life.

AMSOIL Shock Therapy® #5 Light Suspension Fluid – Plush, Predictable Ride Control

AMSOIL Shock Therapy #5 Light Suspension Fluid is a synthetic suspension oil built for riders and drivers who want a plusher, more responsive feel from their shocks and forks. It’s designed for high-performance shocks and forks on circle-track race cars, trucks, ATVs, UTVs, snowmobiles, dirt bikes and street motorcycles.

This light-viscosity formula flows easily, resists fade when things get hot, and helps your suspension stay consistent from the first lap or mile to the last.

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What AMSOIL Shock Therapy #5 Is Designed For

Vehicles And Riding Styles

Shock Therapy #5 Light is aimed at applications where you want less damping and quicker rebound – in other words, a suspension that reacts fast and tracks the ground well. It’s recommended for:

• Circle-track race cars and other competition vehicles
• Dirt bikes and off-road motorcycles
• ATVs and UTVs used on trails, dunes or tracks
• Snowmobiles in cold, rough conditions
• Street bikes and performance road machines
• Cars and trucks needing responsive, high-quality shock fluid

It’s especially popular in front forks and shocks where a light fluid is specified and a more compliant, comfortable feel is desired.

Works With Major Shock And Fork Brands

The fluid is suitable for suspension systems and forks from well-known brands such as Showa, Kayaba, Bilstein, RydeFX, Penske, WP, Race Tech and Custom Axis, where a light #5 fluid is called for.

That makes it easy to service aftermarket performance kits or OEM components without guessing at compatibility.

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Key Benefits Of Shock Therapy #5 Light

High Viscosity Index = Stable Feel As Temperatures Change

Suspension fluid heats up as you ride or race. Cheap oils can thin out, changing damping and making the machine feel loose or unpredictable.

Shock Therapy #5 uses high-viscosity-index synthetic base oils that stay more stable across a wide temperature range.

What that does for you:

• Keeps compression and rebound feel consistent from cold start to fully hot
• Helps prevent “saggy” or mushy behavior late in a race or long ride
• Supports precise, repeatable handling when you’re pushing hard

Helps Prevent Suspension Fade

Fade happens when heat and aeration change how the suspension reacts. The high VI base oils and additives in this fluid help resist viscosity loss and thermal breakdown, so your damping stays closer to what you set in the shop.

Whether you’re pounding whoops, carving ruts or circling a track at speed, that stability means better control and more confidence.

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Controlled Damping And Rebound

Predictable Suspension Behavior

AMSOIL formulates Shock Therapy fluids to give suspension systems a predictable, repeatable feel. The Light #5 version is tuned for:

• Quicker rebound response
• Easier movement over small chop and trail chatter
• A more compliant, “plush” ride

This can help:

• Improve small-bump compliance
• Increase traction over rough surfaces
• Reduce rider fatigue over long days

Anti-Foam Agents For Consistent Performance

Inside a shock or fork, fluid is constantly forced through valves at high speed. That can pull air into the fluid and create foam. Foamy fluid compresses more easily and makes damping feel inconsistent.

Shock Therapy #5 includes anti-foam additives that reduce aeration and foam formation, helping the suspension stay solid and controlled instead of vague or spongy.

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Reduces Friction And Wear Inside Shocks And Forks

Friction Modifiers For Smoother Movement

Every time the suspension cycles, internal parts slide against each other. That friction wastes energy and can make the suspension feel harsh.

Shock Therapy #5 contains friction modifiers that reduce this internal drag, so more of the forces are used for actual damping, not wasted as heat.

Benefits:

• Smoother, more controlled fork and shock action
• Better “feel” at the bars or steering wheel
• Less energy loss, which can help the suspension respond more quickly

Anti-Wear Agents Protect Internal Components

Shocks and forks rely on pistons, shafts, valves, bushings and seals all moving in tight tolerance. Over time, poor fluid can let these parts wear, causing:

• Leaks
• Loss of damping control
• More frequent rebuilds

Shock Therapy #5 includes anti-wear additives that form a protective layer on metal surfaces to help guard against abrasion and scuffing during operation.

This helps:

• Extend the life of shocks and forks
• Keep damping settings accurate longer
• Reduce long-term maintenance costs

Seal Conditioners For Longer Service Life

Suspension seals are critical; when they dry out or harden, they can leak or create stiction. This fluid uses seal conditioners to help maintain seal flexibility and elasticity.

The result:

• Reduced risk of seal-related leaks
• Smoother initial movement (less “stick-slip”)
• Better long-term reliability

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Cold-Weather And All-Season Performance

Excellent Low-Temperature Flow

One of the reasons Shock Therapy #5 is a favorite in snowmobiles and cold-weather ATV/UTV setups is its low-temperature performance. Typical data show a very low pour point (around –53°C / –63°F), which means the fluid stays mobile in harsh winter conditions. performanceoiltechnology.com+2snowmobileoil.co+2

That helps your:

• Shocks start working properly almost immediately
• Suspension avoid that stiff, wooden feel on cold starts
• Machine track better in frozen ruts and hard-packed snow

Preferred For Winter Use And Light Damping Applications

AMSOIL notes that Shock Therapy Light #5 is the preferred choice for winter and for setups where less damping and faster rebound are desired.

That makes it a strong match for:

• Lightweight riders
• Machines that feel harsh with heavier suspension oil
• Fast trail work with lots of small bumps

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Where Shock Therapy #5 Fits In The Line

AMSOIL offers both Shock Therapy #5 (Light) and Shock Therapy #10 (Medium) suspension fluids:

• #5 Light – For quicker, plusher response, less damping, faster rebounds, and cold-weather use
• #10 Medium – For firmer, more controlled damping and slower rebound, often used in heavier machines or where the fork/shock needs more resistance

If your suspension feels too harsh or stiff with a heavier fluid, stepping down to Shock Therapy #5 is often the solution.

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Typical Use Cases

Off-Road And Trail Riders

For ATVs, UTVs and dirt bikes that see:

• Constant trail chop
• Roots, rocks and whoops
• Long days in the saddle

Shock Therapy #5 can make the suspension more forgiving and help the tires stay planted, which improves comfort and control.

Snowmobile Riders

In sleds, this fluid helps:

• Keep shocks active in extreme cold
• Maintain consistent damping during long runs
• Reduce harshness over stutter bumps and moguls

Because it stays fluid at very low temperatures and resists foaming, it’s a popular choice in aggressive snowmobile setups.

Racers And Performance Street Riders

For circle-track cars, performance street bikes and track-day machines, Shock Therapy #5 offers:

• Stable viscosity as damper temperatures rise
• Precise, predictable feedback at the limit
• Protection that helps suspension components last through demanding use

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Practical Tips For Using AMSOIL Shock Therapy #5

(Always follow the shock/fork manufacturer’s instructions and service manual.)

• Confirm viscosity – Check whether your suspension calls for a light (#5) fluid; many tuners specify something like “5W fork oil,” which this product is designed to match or replace.
• Agitate before use – AMSOIL recommends shaking/agitating the fluid before filling to ensure additives are evenly distributed.
• Bleed air carefully – During shock or fork service, make sure all trapped air is removed. Even the best anti-foam package can’t fix a poorly bled damper.
• Follow rebuild intervals – While this fluid helps extend component life, shocks and forks still need periodic service. Stick to the recommended rebuild schedule for your type of riding.

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Who Should Choose AMSOIL Shock Therapy #5 Light Suspension Fluid?

This product is a strong choice if you:

• Want a plusher, more responsive suspension feel
• Ride or race in cold or variable temperatures
• Use shocks or forks that specify a light #5 or similar viscosity
• Need stable damping, minimal fade and reduced foaming under aggressive use
• Care about long-term protection of expensive suspension components

If your machine feels harsh, unpredictable or fatiguing to ride, upgrading to a dedicated race-grade synthetic suspension fluid like AMSOIL Shock Therapy #5 Light can make a very noticeable difference in comfort, traction and control.