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There’s no such thing as a brand of pump gasoline that’s genuinely “better” for a Harley-Davidson than another brand’s gas of the same octane — once you’ve met your bike’s minimum octane requirement, the tank of Shell in your Milwaukee-8 Street Glide isn’t outperforming the tank of Chevron down the road. What actually matters is getting the octane right for your engine and protecting that fuel from the ethanol most pump gas contains. Twin Cam and Milwaukee-8 engines are built for a minimum 91 pump octane; some older Evolution-engine Sportsters and Big Twins were tuned for 87 and can run rougher on premium than on regular. Check your owner’s manual rather than assuming higher is always better. The real shoppable products here are the fuel stabilizers and treatments riders actually add to the tank — to fight the ethanol-related gum, varnish, and corrosion that pump gas causes in a bike that sits between rides, and to keep injectors and carburetors clean on one that’s ridden daily. Here are the real, current products worth keeping in the garage.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | STA-BIL Storage Fuel Stabilizer (32 oz) | $9-$16 per 32 oz bottle | Amazon · eBay |
| 2 | Star Tron Enzyme Fuel Treatment (Star brite) | $10-$20 depending on bottle size | Amazon · eBay |
| 3 | Chevron Techron Concentrate Plus | $12-$18 per 20 oz bottle | Amazon · eBay |
| 4 | Lucas Oil Fuel Treatment (10020) | $3-$9 per 5.25 oz bottle | Amazon · eBay |
| 5 | Sea Foam Motor Treatment (SF-16) | $9-$13 per 16 oz can | Amazon · eBay |
| 6 | Berryman B-12 Chemtool (0116) | $6-$10 per 15 oz can | Amazon · eBay |
| 7 | Gumout Regane Complete Fuel System Cleaner (6 oz) | $6-$10 per 6 oz bottle | Amazon · eBay |
| 8 | Royal Purple Max-Clean Fuel System Cleaner & Stabilizer (20 oz) | $14-$25 per 20 oz bottle | Amazon · eBay |
| 9 | Red Line SI-1 Complete Fuel System Cleaner (15 oz) | $17-$18 per 15 oz bottle | Amazon · eBay |
| 10 | Amsoil P.i. Performance Improver | $17-$25 per bottle | Amazon · eBay |
| 11 | K100 MG Gasoline Treatment with Stabilizer (8 oz) | $10-$13 per 8 oz bottle | Amazon · eBay |
| 12 | Motorcraft PM-5 Fuel Injector Cleaner (gasoline, 8 oz) | $20-$48 depending on retailer | Amazon |
The picks, in detail
STA-BIL Storage Fuel Stabilizer (32 oz)
The standard winter-storage insurance policy. Mix it into fresh gas before the bike sits so ethanol-blended fuel doesn’t turn to varnish in the carburetor or fuel injectors over the off-season.
- 32 oz bottle treats up to 80 gallons
- Rated for ethanol blends up to E10
- Claims to keep fuel fresh up to 24 months
- Also sold in diesel and marine formulas
- Cheap, widely stocked insurance for seasonal storage
- Works in both carbureted and fuel-injected Harleys
- Doesn’t clean deposits that are already there
- Needs to go into fresh fuel, not gas that’s already gone stale
Star Tron Enzyme Fuel Treatment (Star brite)
An enzyme-based treatment instead of a petroleum-solvent one — it actually breaks down ethanol-related gum rather than just slowing it down, which is why storage-heavy riders and boaters both reach for it.
- Enzyme technology, not petroleum solvents
- Concentrated formula: 1 oz treats up to 16 gallons
- Same active formula sold under marine and gasoline labels
- Available from 1 oz single-dose packs up to 32 oz
- Can reverse some existing ethanol gumming, not just prevent it
- A small bottle lasts many tank fills
- Costs more per treatment than a straight stabilizer
- Enzyme-cleanup claims are hard for a rider to verify at home
Chevron Techron Concentrate Plus
Not a stabilizer — a fuel-injector and combustion-chamber cleaner. Run a bottle through the tank of a regularly ridden Harley every few thousand miles to keep injectors and valves carbon-free.
- PEA (polyetheramine) detergent chemistry
- 20 oz bottle treats up to 20 gallons
- Chevron’s own automotive additive formulation
- Also cleans intake valves and combustion chamber deposits
- Real, lab-documented cleaning effect, not just a marketing claim
- Good complement to (not a replacement for) a stabilizer for storage
- Won’t protect a stored bike’s fuel system by itself
- Less necessary if you already run Top Tier gasoline
Lucas Oil Fuel Treatment (10020)
An upper-cylinder lubricant and mild injector cleaner that a lot of V-twin owners add every few tanks to fight the drier lubricity of modern ethanol-blended pump gas.
- 5.25 oz bottle treats one tank of fuel
- Upper-cylinder lubricity additive
- Long-running formula popular in the V-twin and off-road community
- Sold individually or in 6-packs
- Very low cost per tank
- Long track record among Harley owners
- Fuel-mileage improvement claims are more marketing than measured fact
- Not a long-term storage stabilizer
Sea Foam Motor Treatment (SF-16)
The do-everything can: part stabilizer, part injector/carb cleaner, part upper-cylinder lube. A reasonable single product for a Harley that sits between rides as much as it gets ridden.
- 16 oz can treats up to 16 gallons of fuel
- Combined stabilizer + cleaner + top-end lube in one product
- Also rated safe to add to crankcase oil
- Sold singly or in multi-packs
- One product covers both cleaning and storage duty
- Sold at nearly every auto parts store, easy to find on the road
- Jack-of-all-trades — a dedicated stabilizer or dedicated cleaner each edges it out at their one job
- Stronger petroleum smell than enzyme-based products
Berryman B-12 Chemtool (0116)
A stronger solvent-based carb and injector cleaner, for when a Harley has already been sitting with stale gas and the carburetor or throttle body needs to be actually cleaned out, not just protected going forward.
- 15 oz can, carburetor- and injector-safe solvent blend
- Doubles as a general shop carb cleaner
- Long-running B-12 Chemtool formula
- Sold singly or in bulk packs
- Stronger cleaning action than mild enzyme treatments on a gummed-up carburetor
- Inexpensive
- Stronger solvent smell than enzyme-based products
- Overkill for routine maintenance on a bike ridden regularly
Gumout Regane Complete Fuel System Cleaner (6 oz)
A budget injector/valve cleaner from one of the most recognizable names in the category — a reasonable once-in-a-while treatment for a Harley that’s picked up hesitation or rough idle from carbon buildup.
- 6 oz bottle treats up to 20 gallons
- PEA-based detergent formula
- Also sold in a High Mileage variant for older engines
- Widely stocked at gas stations and auto parts stores
- Cheapest injector cleaner in this lineup
- Available almost anywhere, useful for a treatment picked up mid-trip
- Smaller bottle size than most competitors here relative to treatment volume
- Marketing claims run ahead of independently verified results, as with most drugstore-aisle cleaners
Royal Purple Max-Clean Fuel System Cleaner & Stabilizer (20 oz)
A combined cleaner-and-stabilizer from Royal Purple’s synthetic-lubricant line, aimed at riders who want one product that both cleans injectors and protects fuel during storage.
- 20 oz bottle, treats a full tank
- Combined injector cleaner and fuel stabilizer in one formula
- Safe for both gasoline and diesel engines
- Sold singly or in multi-packs
- Covers both cleaning and stabilizing duty like Sea Foam, from a brand better known for synthetic oil quality
- Larger 20 oz bottle than most single-dose cleaners here
- Priced above straightforward stabilizers like STA-BIL for the same core stabilizing function
- No independent third-party test data beyond Royal Purple’s own claims
Red Line SI-1 Complete Fuel System Cleaner (15 oz)
A synthetic-oil-industry brand’s fuel system cleaner, popular with performance-minded riders for cleaning injectors, carburetors, and combustion chamber deposits in one treatment.
- 15 oz bottle
- Cleans injectors, carburetors, valves, and combustion chamber deposits
- Also includes corrosion prevention additives
- From Red Line’s synthetic lubricants lineup
- Strong reputation among performance and racing communities for actual cleaning results
- Addresses combustion-chamber deposits that milder cleaners don’t target
- Priced above Gumout and Berryman for a similar cleaning job
- Not a long-term storage stabilizer
Amsoil P.i. Performance Improver
A concentrated, higher-strength injector and combustion-chamber cleaner marketed on cleaning power rather than price — for a Harley that’s built up real carbon deposits, not just routine upkeep.
- Treats up to 20-21 gallons per bottle depending on size
- Concentrated PEA detergent chemistry
- Marketed toward removing existing deposits, not just preventing new ones
- Sold through Amsoil dealers and some general retailers
- Amsoil’s own testing claims some of the strongest deposit-removal numbers in this category
- Good option for a bike you just bought used with an unknown maintenance history
- More expensive per treatment than Gumout, Techron, or Berryman
- Less convenient to find on a shelf than the mainstream auto-parts-store brands
K100 MG Gasoline Treatment with Stabilizer (8 oz)
A combined stabilizer-and-treatment that’s popular specifically in the powersports and small-engine world (motorcycles, ATVs, marine), not just a repackaged automotive additive.
- 8 oz bottle, treats multiple tanks
- Combined stabilizer and moisture-control formula
- Formulated for small-displacement gasoline engines
- Also sold in a diesel-specific K100-MD version
- Purpose-marketed toward motorcycles and powersports rather than a generic car additive relabeled for bikes
- Moisture-control claim specifically targets ethanol’s water-absorption problem
- Smaller brand with less mainstream retail presence than STA-BIL or Sea Foam
- 8 oz bottle needs replacing more often than the 16-32 oz options here
Motorcraft PM-5 Fuel Injector Cleaner (gasoline, 8 oz)
Ford’s own-brand gasoline injector cleaner (not to be confused with Motorcraft’s diesel-only PM-22 cetane booster) — a factory-grade cleaner sold through the same network that services Fords and plenty of Harleys both.
- 8 oz bottle
- PEA detergent chemistry, Ford’s factory-recommended formulation
- Gasoline-specific — separate from Motorcraft’s diesel cetane booster line
- Sold through Ford dealers and general auto parts retailers
- OEM-grade formulation with a long service history in Ford’s own dealer maintenance programs
- Straightforward single-purpose injector cleaner, no stabilizer claims to evaluate separately
- Priced well above the Gumout/Berryman tier for a comparable cleaning job
- Less specifically marketed toward motorcycles than K100 or Star Tron
Buying tips
- Check your owner’s manual, not the pump: Twin Cam and Milwaukee-8 engines typically call for a 91 minimum pump octane, while some older Evolution-engine models are tuned for 87 and can run worse — not better — on premium.
- Ethanol-blended E10 is the real issue, not the octane number. E10 absorbs moisture and gums up carburetors and injectors faster than ethanol-free fuel, especially on a bike that sits for weeks between rides.
- If a station near you sells ethanol-free (non-oxygenated) gasoline, it’s worth seeking out for a bike that’s stored seasonally, even at a slightly higher price per gallon.
- Add a stabilizer to fresh fuel before storage, not to gas that’s already sat for months — once ethanol has already broken down and gummed the system, you need a cleaner, not a stabilizer.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.