Your engine's top-end is sparsely lubricated and prone to the development of performance-robbing deposits. It's also highly susceptible to corrosion, an issue compounded by the prevalence of ethanol in today's fuel. AMSOIL Upper Cylinder Lubricant is designed to solve those is - sues. Its AMSOIL-exclusive, powerful formulation helps maximize en - gine power and performance while increasing engine life. And unlike competing fuel additives, AMSOIL Upper Cylinder Lubricant works. 1 Based on independent testing of AMSOIL Upper Cylinder Lubricant, Lucas Upper Cylinder Lubricant and Sea Foam Motor Treatment obtained on 2/13/2019 using the ASTM D6079 modified for use with gasoline. *All tradmarked names and images are the property of their respective owners and may be registered marks in some counries. No affiliation or endorsement claim, express or implied, is intended by their use. • Lubricates fuel system and upper cylinders • Fights ethanol-related corrosion • Helps keep injectors clean • Compatible with capless fuel systems Base Fuel
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AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor (UCL) is a gasoline fuel additive engineered to restore the lubricity that ethanol-blended pump fuel takes away, defend top-end engine surfaces against corrosion, and keep injectors and combustion chambers clean. The 6 oz. bottle treats up to 25 gallons of gasoline and is designed for use with every fill-up in cars, light trucks, and other gasoline-powered vehicles.
Adds lubricity that ethanol fuel cannot provide
The intense heat of combustion and the design of the oil-control piston ring leave the top of each cylinder sparsely lubricated. Upper Cylinder Lubricant supplies a film at the rings, valve stems, and fuel-system metals to fight piston-ring and cylinder wear, helping preserve compression and horsepower. Lubricity improvers also protect fuel injectors and other fuel-system components from wear so the engine retains performance and service life.
Upper Cylinder Lubricant delivers 18 percent more lubricity than Lucas Upper Cylinder Lubricant and 20 percent more than Sea Foam Motor Treatment, based on independent testing of all three products obtained on 02/13/2019 using ASTM D6079 modified for use with gasoline. Smaller wear-scar diameter indicates better lubricity. The treated test fuel produced a 640 µm wear scar with Upper Cylinder Lubricant, compared with 786 µm for Lucas, 803 µm for Sea Foam, and 807 µm for the untreated E10 base fuel.
Inhibits corrosion driven by ethanol-blended fuel
Upper Cylinder Lubricant uses corrosion inhibitors that coat metal surfaces, block out moisture, and stop deterioration before it starts. This matters most when the tank sees gasoline that contains ethanol, since ethanol attracts water and accelerates corrosion of fuel-system metals. Slowing that corrosion reduces wear in the engine top-end, helps guard against compression loss, and supports steady power and fuel economy across long ownership.
Keeps injectors and combustion chambers clean
Detergent additives in Upper Cylinder Lubricant maintain injector cleanliness and help preserve clean combustion chambers when the additive is used with each tank of fuel. The role here is preventive maintenance. AMSOIL P.i. Performance Improver is the matching cleaning product, designed to attack and remove stubborn injector deposits that already reduce power and economy, while Upper Cylinder Lubricant works alongside it to retain the gains and limit redeposit between treatments.
Capless fuel-system compatibility
Many late-model vehicles use capless fuel necks, and the threads on most additive bottles can struggle to open the inner flap and become awkward to remove. The Upper Cylinder Lubricant bottle is shaped to be fully compatible with capless fuel systems. Inserting the bottle, pouring the full dose, and removing it cleanly is straightforward at the pump.
Compatible with modern gasoline hardware and fuels
Upper Cylinder Lubricant is safe for use with catalytic converters, oxygenated gasoline, and E85 fuel, which makes it suitable for the gasoline blends sold across the United States and Canada market. It targets the lubricity, corrosion, and detergency gaps that are common to today's port and direct-injected gasoline engines running on E10, E15, or flex-fuel blends.
Recommended applications and treat rate
Upper Cylinder Lubricant is formulated for cars and trucks running gasoline. For best results, add a full 6 oz. bottle to a tank that is almost empty, then refill so the additive mixes with fresh fuel as the tank fills.
Treat up to 25 gallons of gasoline per 6 oz. bottle, added at fill-up.
For larger gas tanks, treat with two bottles maximum. Using more than two bottles is not recommended.
For best results, use with every tank of fuel and avoid refilling the tank until it is almost empty.
Do not use with two-stroke engines or diesel engines.
Upper Cylinder Lubricant is intended as a complement to a complete maintenance routine. Owners who want to remove existing injector and combustion-chamber deposits can pair it with AMSOIL P.i. Performance Improver as a periodic deep clean, and continue Upper Cylinder Lubricant with each tank for ongoing protection. The additive is compatible with normal pump-grade gasoline and does not replace scheduled engine oil and filter changes.
Order Upper Cylinder Lubricant Corrosion Inhibitor
Upper Cylinder Lubricant Corrosion Inhibitor is available as a 6 oz. bottle (product code UCLCN-EA) and a case of twelve 6 oz. bottles (UCLCN-CA). All AMSOIL products are backed by the AMSOIL Limited Warranty. To match the right AMSOIL maintenance products to a specific car or truck, use the AMSOIL vehicle lookup, then review the related fuel-additive positioning in the fuel additive products, and order AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor.
Customer reviews
4.8Based on 374 reviews
Fuel Lubricate
I Run Premium fuel in my 2022 RAM 1500 the upper cylinder lubricate you are supposed to use it in every tank. I do believe that it works as it should use it every second tank fill. The long neck really helps with the capless fuel cap. I would recommend this.
By Robin from Yorkton Sk. on May 11, 2026.
Would recommend this to a friend.
Best additive
I use it once a month to give my engine extra protection. I have 150,000 km on it and my engine stays as quiet as a brand new car.
By Ricardo from Ottawa on April 28, 2026.
Would recommend this to a friend.
Amazing product, it works,
run this every second fill up engine runs amazing , smooth, and better fuel economy
By Charles from spruce grove , alberta on April 27, 2026.
Upper Cylinder Lubricant adds a film at the top of the cylinder, on valve stems, and inside the fuel system to fight wear that low-lubricity ethanol-blended pump fuel can cause. It also includes corrosion inhibitors to coat metal surfaces against moisture and detergents that maintain injector cleanliness when used with every tank.
How often should Upper Cylinder Lubricant be used?
For best results, treat with every tank of fuel. A 6 oz. bottle treats up to 25 gallons of gasoline. Larger gas tanks should be treated with two bottles, and using more than two bottles is not recommended.
Is Upper Cylinder Lubricant safe with E10, E15, or E85 gasoline?
Yes. Upper Cylinder Lubricant is safe for use with catalytic converters, oxygenated gasoline, and E85 fuel. The corrosion inhibitors are particularly useful with ethanol-blended fuel because ethanol attracts water and accelerates corrosion of fuel-system metals.
Can Upper Cylinder Lubricant be used in diesel or two-stroke engines?
No. Upper Cylinder Lubricant is formulated for gasoline cars and trucks. It should not be used with two-stroke engines or diesel engines.
Does it replace AMSOIL P.i. Performance Improver?
No. The two products solve different problems. AMSOIL P.i. Performance Improver is a concentrated cleaner designed to attack and remove stubborn injector deposits that already reduce power and fuel economy. Upper Cylinder Lubricant is the maintenance additive that helps preserve injector and combustion-chamber cleanliness once the deposits are gone, and it is intended for use with each tank of fuel.
Will Upper Cylinder Lubricant work in a capless fuel system?
Yes. The Upper Cylinder Lubricant bottle is shaped for capless fuel necks and is designed to insert, pour, and remove cleanly without struggling against the inner flap that defeats many additive bottles.
How is the lubricity claim measured against Lucas and Sea Foam?
The 18 percent and 20 percent advantages come from independent testing of Upper Cylinder Lubricant, Lucas Upper Cylinder Lubricant, and Sea Foam Motor Treatment obtained on 02/13/2019, run on ASTM D6079 modified for use with gasoline. In that test, smaller wear-scar diameter indicates better lubricity, and the treated fuel produced a 640 µm scar with Upper Cylinder Lubricant compared with 786 µm for Lucas, 803 µm for Sea Foam, and 807 µm for untreated E10 base fuel.
