The 10 Best Fuel System Cleaners
Updated by · How we research
Ten fuel system cleaners compared by detergent, dose and engine type. Chevron Techron Concentrate Plus leads for most gas cars; Red Line SI-1 suits deep cleans. When users buy our independently chosen editorial picks, we may earn commissions to help fund the Wiki.
In AAA's lab study, gas that isn't Top Tier left about 19 times more engine deposits than Top Tier gas, so the first fix is often at the pump. A bottled cleaner helps most with light buildup, rough idle and hesitation in gas engines. It does little for the intake valves of direct-injection engines, and it can't fix a dead injector.
From the manual
- Chevron's schedule is a bottle every 3,000 miles or at each oil change, and never more than twice per oil change. p. 2
- It's recommended for direct-injected gas engines, gasoline hybrids and ethanol blends, and not recommended for diesel engines. p. 2
- Two-strokes, mowers, motorcycles and marine gas engines are fine too; treat their fuel at one ounce per gallon. pp. 1-2
- The safety data sheet rates it a skin sensitizer that can be fatal if swallowed and drawn into the lungs, so wear gloves. safety data sheet, pp. 1-2
Why the Chevron Techron Concentrate Plus is our top pick
No independent test separates our pick from our runner-up, the Red Line SI-1, so the call rests on what each maker documents, and Chevron's paperwork covers more engines with a simpler routine. Its data sheet recommends the formula for port- and direct-injected gas engines, gasoline hybrids and ethanol blends,1 including E85,1 and also clears it for two-stroke, mower, motorcycle and marine engines.1
The dose is one ounce per gallon,2 so the 20-ounce bottle treats a 20-gallon tank in one go. Chevron then calls for a bottle every 3,000 miles or at each oil change, and never more than twice per oil change.1 The runner-up asks for more attention: a full bottle for the first cleanup, then half a bottle every 1,500 miles,3 twice as often. Our pick has one extra of its own: Chevron says it can clean sulfur corrosion off fuel-gauge senders, a possible cause of a faulty gauge.1
The runner-up still earns its place. Its sheet says it cleans every kind of injector, direct-injection ones included, and adds a synthetic upper-cylinder lubricant,3 which is why it's our pick for a one-time deep clean, and its maker sells the same chemistry in a small powersports bottle.3 Both makers say their formulas won't harm oxygen sensors or catalytic converters,1,3 both are gasoline formulas, and every performance claim on both sheets is the maker's own.
| Chevron Techron Concentrate Plus | Red Line SI-1 | |
|---|---|---|
| Dose | 1 oz per gallon | Full 15 oz bottle per 20 gal |
| Repeat use | Every 3,000 mi or oil change | Half bottle every 1,500 mi |
| Engines the maker lists | Gas incl. direct injection, hybrids, E85, small engines | Gas, all injector types incl. GDI |
| Extra the maker claims | Cleans fuel-gauge sender corrosion | Upper-cylinder lubricant |
| Sensor and converter safe | Yes, per Chevron | Yes, per Red Line |
Sources
- Chevron Techron Concentrate Plus 1Product data sheet FA-41, September 2025 (PDF), pp. 1–2, 1, 2 2Fuel additives portfolio, treat rates (PDF)
- Red Line SI-1 3Product information sheet (PDF)
From the manual
- Pour it in before filling: a full bottle into a nearly empty tank, then up to 20 gallons of gas. p. 1
- Upkeep is half a bottle every 1,500 miles, and Red Line calls it safe for continual use. p. 1
- Red Line claims it cuts an engine's octane need by up to two points. p. 1
- The same chemistry comes in a 4-ounce bottle for powersports engines. p. 1
Compare the specs
Swipe the table sideways to see every column.
| Product | Fuel (on the label) | Dose (maker's directions) | How often (maker's advice) | Direct-injection engines (maker's claim) |
|---|---|---|---|---|
| 1. Chevron Techron Concentrate Plus | Gas only | 1 oz per gal | 3,000 mi or oil change | Recommended |
| 2. Red Line SI-1 | Gas | 15 oz per up to 20 gal | Half bottle per 1,500 mi | Yes, incl. GDI injectors |
| 3. BG 44K Platinum | Gas | 11 oz per 13-20 gal | — | — |
| 4. Liqui Moly Pro-Line | Gas | 500 ml per up to 18 gal | At each service | Yes, direct and port |
| 5. Gumout High Mileage | Gas | 6 oz per up to 21 gal | Every 3,000 mi | Not claimed |
| 6. Sta-Bil In-Season Protection | Gas | 1 oz per 5 gal | Every fill-up | — |
| 7. Sea Foam Motor Treatment | Gas and diesel | 1 oz per gal; 2+ to clean | 1-2 cans per 2,000-5,000 mi | — |
| 8. Lucas Oil Renewal Kit | All fuel types | 1 bottle per fill-up | 4 fill-ups in a row | — |
| 9. Royal Purple Max-Clean | Gas and diesel | 1-2 oz per gal | 10,000 mi or yearly | Made for it |
| 10. Star Brite Star Tron | Gas formula | 1 oz per 16 gal | Every fill-up | — |
Doses and intervals are the makers' own directions; check the label of the size you buy. A dash means the maker documents we read give no U.S. figure.
Sources
- Chevron Techron Concentrate Plus Product data sheet FA-41 (PDF) Fuel additives portfolio, treat rates (PDF)
- Red Line SI-1 Product information sheet (PDF)
- BG 44K Platinum PN 208M page, BG Middle East
- Liqui Moly Pro-Line Gasoline System Cleaner page
- Gumout High Mileage Maker page and directions
- Sta-Bil In-Season Protection Gold Eagle maker page
- Sea Foam Motor Treatment HOW 2 sheet for gas and diesel tanks (PDF)
- Lucas Oil Renewal Kit Maker page and directions Products catalog, Canada, p. 4 (PDF)
- Royal Purple Max-Clean Product data sheet (PDF)
- Star Brite Star Tron Concentrate gas formula page
From the manual
- BG's dose chart scales from 50 ml for up to 4 gallons to the full 11-ounce can for 13 to 20 gallons. maker page
- BG marks it "for professional use" and accepts no liability for excessive use or misuse. maker page
- BG's Middle East page suggests one can in a full tank every 10,000 km, about 6,200 miles. maker page
From the manual
- One 500 ml can treats up to 70 liters, about 18 gallons, poured straight into the tank. maker page
- Liqui Moly lists it for direct, port and combined gasoline injection systems. maker page
- Its suggested schedule: at each service, after fuel-system repairs and after a shop JetClean flush. maker page
- The U.S. can asks for at least 7 gallons of fuel with it for best results. U.S. label, FCP Euro
From the manual
- Add the whole bottle to a nearly empty tank, fill with up to 21 gallons, and run it near empty before refilling. maker page
- Gumout's interval is every 3,000 miles, not every tank. maker page
- The page lists port-injector, valve and port cleaning; it doesn't claim to clean direct-injection engines. maker page
- Gumout says it won't void a carmaker's warranty and is safe with turbochargers and superchargers. maker page
From the manual
- One ounce treats up to five gallons, and Sta-Bil means it for every fill-up. maker page
- In a stored vehicle one dose keeps fresh fuel stable up to 12 months; the red Storage formula is for longer. maker page
- Overdosing is fine up to four times the label amount; past that, Sta-Bil says to dilute the fuel. maker page
- The code on the back of the bottle dates it: the first two digits are the year, the next three the day. maker page
From the manual
- The upkeep and storage dose is one ounce per gallon, so a pint can treats up to 16 gallons. p. 1
- To clean, Sea Foam says use at least two ounces per gallon, up to a half-and-half mix with fuel. p. 1
- For fuel older than three weeks, add it to every tank; otherwise one or two cans every 2,000 to 5,000 miles. p. 1
- The safety data sheet rates it highly flammable and lists up to 25 percent isopropanol. safety data sheet, pp. 1-2
Sea Foam HOW 2 sheet: adding Sea Foam to gas and diesel (PDF)
From the manual
- The box holds one Deep Clean bottle for the first fill-up and three Upper Cylinder Lubricant and Injector Cleaner bottles. p. 4
- Lucas lists the kit for all vehicles and fuel types, diesel included. p. 4
- Each bottle goes in whole, before or after filling, at four fill-ups in a row. maker page
From the manual
- Pour the whole bottle into a nearly empty tank just before refueling; one bottle treats up to 20 gallons. p. 2
- Royal Purple suggests a treatment every 10,000 miles or once a year, whichever comes first. p. 2
- It's recommended for gasoline and diesel engines and also stabilizes stored gas and ethanol blends. pp. 1-2
- Its deposit claim rests on a track test against an unnamed competitor, with no outside lab named. p. 1
From the manual
- Add it just before each fill-up; Star Brite says overdosing does no harm. maker page
- The concentrate is dosed at one ounce per 16 gallons of fuel. maker page
- Star Brite says it stabilizes fuel up to two years and disperses water to fight phase separation. maker page
Editor's Notes
November 5, 2026, by Ezvid Wiki Editors:
This pass checked every pick against its maker's own sheets, among them Chevron's Techron data sheet and the Red Line, Royal Purple and Sea Foam dosing sheets. We added a spec table, a section on why Techron leads and notes from those documents. We also fixed three claims that the makers' own documents contradict: Techron as a stabilizer for stored gas, Gumout as an every-tank dose, and a diesel list that left out Royal Purple.
October 23, 2026, by Ezvid Wiki Editors:
Chevron Techron Concentrate Plus moves to the top. Its detergent cleans injectors, intake valves and combustion chambers, one bottle doses a full tank, and it's sold almost everywhere. Red Line SI-1 and BG 44K Platinum follow for deeper cleanups.
The hard evidence in this field is mostly about gasoline, not bottles. AAA's lab work showed how much detergent-rich gas matters, and Motor Trend's injector flow check of one pour-in cleaner found no change on an older engine. So we ranked by the detergent each formula uses, the makers' own dosing sheets and long-running owner patterns, and we say where a claim is only the maker's.
We dropped Marvel Mystery Oil Ultimate because the listing we link to had run out of stock, though Marvel still sells it, and Lubegard 77012 Booster because so little stands behind it. Royal Purple Max-Clean stays, but now as a two-pack, since the single-bottle listing is gone. The old Sta-Bil 360 Protection is now called Sta-Bil In-Season Protection. New are Liqui Moly Pro-Line for import owners and Gumout High Mileage as the low-cost habit.
Diesel owners: the list is gasoline-first. Sea Foam Motor Treatment, the Lucas Oil Renewal Kit and Royal Purple Max-Clean are the picks here that list diesel engines.
Earlier notes
December 7, 2020, by Brett Dvoretz:
During this latest update, we made a few changes to reflect what we feel are better offerings for several reasons. One example of this is eliminating Lucas Oil 10512 Deep Clean and Lucas Oil 10013 Lubricant as separate options, and instead including the Lucas Complete Renewal Kit, which comes with a bottle of each of this effective formulas. [2026 update: today's kit holds one Deep Clean bottle and three bottles of Upper Cylinder Lubricant and Injector Cleaner.] Together, these will clean every aspect of your engine's fuel system, from the injectors to the combustion chamber, which should result in improved performance in across many areas. This freed up a spot to add Sea Foam SF-16, which has proven to be very effective at both removing and preventing deposits. It has also shown to improve cold and hot combustion pressure, which makes an engine start quicker and more powerful. [2026 update: Sea Foam's own dosing sheet describes it as a petroleum solvent blend for gum and varnish, without harsh detergents, and we found no published test behind the combustion-pressure claim.]
Another change was to replace Star Brite Star Tron Enzyme with Star Brite Star Tron Enzyme Concentrate. The latter comes in a 32-ounce bottle that is enough to treat over 500 gallons of gasoline. We feel this is not only more economical, but also more practical than the tiny one-ounce bottles the former comes in that can only treat six gallons. Other than one being more concentrated than the other, these are both equally effective at preventing phase separation, rejuvenating old fuel, and removing gunky buildup.
Based on some independent tests, we decided to remove STP 17437 Ultra and added Marvel Mystery Oil Ultimate. While there was nothing inherently wrong with the former, and they are both good at removing and preventing valve and cylinder deposits, the latter is just more versatile. Not only is it suitable for use in petrol and diesel engines, but it can also be used in hybrids and gasoline direct injection systems. Additionally, it doubles as an oil additive, allowing you to use a single solution for many of your maintenance needs.
April 29, 2019, by Brett Dvoretz:
For the novice, trying to choose a fuel system cleaner can be a bit like trying to decipher Latin, they have no idea where to start. Luckily, we've got you covered and have put together a list of the best options, as well as tried to provide some guidance regarding the best usage of each. If you have a diesel engine, we recommend looking at Lubegard 77012 Booster and Lucas Oil 10013 Lubricant. That isn't to say these options wouldn't also be suitable for gasoline engines, they are just safe and very effective on diesels too. If you have an upcoming emissions test and are worried about passing, grab yourself some Royal Purple 11723 Max-Clean. You'll realize a marked reduction in the amount of harmful emissions leaving your vehicle, and it takes effect very quickly. [2026 update: the emissions benefit is Royal Purple's own claim; we found no independent test of it.] If you think you car is stumbling because of restricted flow through your injectors, we recommend trying BG 44K Platinum. Along with BG 44K Platinum, Chevron Techron Concentrate and Red Line Complete SI-1 both work very well for high-performance engines. If you need something for your boat, you should probably take a look at STP 17437 Ultra, and if you want something for small outdoor engines, say a lawnmower or string trimmer, we recommend Star Brite Star Tron Enzyme.
Special Honors
Top Tier Gasoline Top Tier is a fuel standard backed by several automakers that requires more detergent than the EPA minimum. Filling up at a Top Tier station is the cheapest way to keep injectors and valves clean, and its site lists the gas brands that qualify. toptiergas.com
What A Bottle Can And Can't Clean
Their fuel sprays straight into the cylinder, so it never washes the intake valves, and the carbon there comes from oil vapor.
A pour-in cleaner works by riding along with the fuel, so it can only clean what the fuel touches: the injectors, the intake valves on older port-injected engines, and the top of the pistons. It helps most with light deposits that cause a rough idle, hesitation or a small drop in mileage.
It won't revive an injector that's badly clogged or leaking. In a 2011 Motor Trend check, a well-known pour-in cleaner left the flow of a 1994 Integra's injectors unchanged, though they were close to spec to begin with. John Park, an injector technician of 18 years at RC Engineering, told the magazine that effective cleaning takes stronger chemicals than stores can legally sell for emissions-controlled cars. GM's 2024 service bulletin doesn't endorse shop injector cleaning as routine maintenance; for prevention it points owners to Top Tier gas and a tank of its own fuel system treatment at each oil change.
Direct-injection engines are a special case. Their fuel sprays straight into the cylinder, so it never washes the intake valves, and the carbon there comes from oil vapor. As AA1Car explains, tank additives do little for those valves; a shop walnut-blasting or induction cleaning is the usual fix. A bottle may still keep the injector tips clean.
The cheapest prevention is the gas itself. In AAA's 2016 study, non-Top Tier gasolines left 19 times more deposits after a simulated 4,000 miles, and Top Tier gas cost only about three cents a gallon more on average at the time.
Shock Dose, Every-Tank Treatment Or Stabilizer
Bottles fall into three groups. Concentrates are meant for an occasional strong dose: Red Line says to pour a full bottle into a nearly empty tank and refill up to 20 gallons, then use half a bottle every 1,500 miles. BG Products gives an 11-ounce pour for 13 to 20 gallons and smaller pours for smaller tanks.
Every-tank treatments use a small dose at each fill-up. They cost little per tank and suit a car that's already running well. A solvent blend like Sea Foam is dosed at about an ounce per gallon and doubles as a stabilizer and a carburetor cleaner.
Stabilizers and enzyme treatments are for fuel that sits: boats, mowers, generators and seasonal cars. They keep gas from going stale and fight water in ethanol blends, but they're not strong injector cleaners.
Whatever you buy, follow the label dose. Chevron says to use Techron no more than twice per oil change, and Royal Purple puts its maximum effective dose at two ounces per gallon. Sea Foam is the exception: its maker says a stronger mix cleans harder. Most makers say to add the bottle before you fill so the fuel mixes it in.
Gas, Diesel And Safety
Most concentrates are for gasoline only, so read the label before using one in a diesel. Of the picks here, Sea Foam, the Lucas Oil kit and Royal Purple Max-Clean list both fuels. Diesel owners who need a cetane boost or anti-gel protection should look at a diesel-specific treatment.
Fuel additives sold for road vehicles have to be registered with the EPA, but registration isn't a seal of approval: federal rules bar makers from presenting it as an endorsement.
These are flammable or combustible liquids, and most are harmful or fatal if swallowed, because they can get into the lungs. Store them upright, away from heat and out of reach of children, and never siphon by mouth. Liqui Moly's U.S. can and Sta-Bil also carry California Prop 65 warnings. Pour into the fuel tank only, unless the label says a cleaner also goes in the oil.
How we researched this
Twenty fuel system cleaners and treatments made the first cut, and the ten here were checked against their makers' own paperwork: Chevron's Techron Concentrate Plus data sheet FA-41 and safety data sheet, Red Line's SI-1 information sheet, Royal Purple's Max-Clean data sheet, Sea Foam's HOW 2 dosing sheet and safety data sheet, Lucas's catalog entry for the 10966 kit, and the maker pages for Gumout, Sta-Bil, Liqui Moly, BG and Star Brite. AAA's 2016 Top Tier study, GM's 2024 service bulletin on injector cleaning and detergent additives, and Motor Trend's 2011 injector flow check shaped the buyer's guide. No CPSC recall turned up for these brands; the only Health Canada actions we found were labeling recalls, of Sea Foam cans sold in Canada without the required hazard labels in 2011 and of a Sta-Bil Storage bottle, a different formula, in 2023.
Sources (22)
- AAA: Not all gasoline is created equal (2016)
- Motor Trend: fuel system cleaners, fact or fiction
- AA1Car: intake valve deposits in GDI engines
- Red Line: SI-1 product information sheet
- BG Products: BG 44K Platinum
- Liqui Moly: Pro-Line Gasoline System Cleaner
- Sea Foam: adding Sea Foam to gas and diesel fuel
- Sea Foam Motor Treatment SDS
- Lucas Oil: Complete Fuel System Renewal Kit
- Royal Purple: Max-Clean product data sheet
- EPA: registration of fuels and fuel additives
- Top Tier Gasoline
- Chevron: Techron Concentrate Plus data sheet FA-41
- Chevron: Techron fuel additives portfolio
- Gumout: High Mileage Fuel Injector Cleaner
- Gold Eagle: Sta-Bil In-Season Protection
- BG Middle East: 44K Platinum (PN 208M)
- Lucas Oil: products catalog (Canada)
- Star brite: Star Tron Enzyme Fuel Treatment, concentrate gas formula
- GM service bulletin 04-06-04-051I (2024)
- eCFR: 40 CFR 79.21, fuel additive registration
- Health Canada: Sea Foam Motor Treatment recall (2011)
Frequently asked questions
Do fuel system cleaners actually work?
They help with light deposits that cause a rough idle or hesitation, and they keep a clean engine clean. They don't fix a badly clogged or failing injector; that needs a shop cleaning or a new part. GM, for one, rejects shop injector cleaning as routine maintenance and recommends Top Tier gas plus a tank of its own treatment at each oil change.
How often should I use a fuel injector cleaner?
Follow the label. Chevron says every 3,000 miles or at each oil change for Techron, Red Line suggests half a bottle every 1,500 miles after a full first dose, and every-tank treatments add a small amount at each fill-up. If you buy Top Tier gas, an occasional bottle is plenty.
What is the best fuel system cleaner for diesel engines?
Most strong concentrates are for gas only. Sea Foam Motor Treatment, the Lucas Oil Renewal Kit and Royal Purple Max-Clean list diesel engines too; for cold-weather gelling or cetane, use a diesel-specific treatment.
Do cleaners work on direct-injection engines?
Partly. They can keep injector tips clean, but the fuel never touches the intake valves in a direct-injection engine, so carbon there usually needs a shop induction or walnut-blast cleaning.
Will a fuel additive void my car's warranty?
Some makers, such as Gumout, say theirs won't. Check your owner's manual, which may recommend Top Tier gas or a specific additive.
Is Top Tier gas better than using an additive?
For prevention, yes. In AAA's 2016 lab test, non-Top Tier gas left 19 times more deposits, and Top Tier cost only about three cents more per gallon on average then.
