Best Octane Booster for Car (2026)

Compared on paper

Specifications are manufacturer rated, as published on each listing and collected 28 October 2026. Where a listing contradicts itself, the title and bullets carry the facts.

How the points were given

The Shop Score weighs performance, build, value, safety and warranty. For octane boosters, safety would cover stated safety certifications; none of the 5 listings states one, so every safety score is 0. Only the K&N listing states a warranty term, at 3 Months. How we pick explains the weights.

Scores run from 9.2 to 9.8: each product’s point total is placed on that range, so more points always means a higher score. Safety counts only for powered gear or where the listing states safety features; where it does not apply, the score is taken over the remaining 90 points.

What the listings tell you

5 listings, and the gaps matter as much as the claims. Only 2 state an octane figure: BOOSTane at up to 116, and Rislone at over 20 points or 2 rating numbers. The other 3 raise octane without stating a figure. Only 3 state a treat volume: Rislone at up to 20 gallons, K&N at up to 18, and STP at up to 15; BOOSTane and Lucas state no treat volume. Only 2 state safe use on catalytic converters and oxygen sensors: Rislone and K&N. Only 1 carries a warranty term: K&N at 3 Months. And 1 is not street-legal at all: BOOSTane. Lucas narrows its audience the other way, to engines and vehicles not equipped with emissions aftertreatment systems.

Buying guide: the best octane booster for car

Octane claims: points, numbers and race fuel

Read the claim before the bottle. BOOSTane states octane up to 116 and calls the result a race fuel equivalent for high-performance race engines. Rislone states typical results over 20 points or 2 rating numbers, with the highest concentrate of real MMT allowed for street use, per the listing. Lucas, STP and K&N state no octane figure: Lucas claims knock control and higher MPG in high compression engines, STP higher octane with intake cleaning, and K&N higher octane with injector cleaning. A figure beats a claim when comparing bottles, but a figure for racing does not help a street car if the bottle is not street-legal.

Treat volume: gallons per bottle

Treat volume decides how far a bottle goes. Rislone states one bottle treats up to 20 gallons, K&N a 16 oz bottle treats up to 18 gallons, and STP one 5.25 fl oz bottle treats up to 15 gallons, poured in full before or after fueling. BOOSTane and Lucas state no treat volume. STP adds a routine: use the additive regularly at every fill-up. Match the bottle to the tank before pouring.

Street use, racing use and catalytic converters

Street legality splits this list. BOOSTane is not street-legal and is engineered for racing, for naturally aspirated or forced induction high-performance engines, with anti-corrosion properties against ethanol and carbon buildup. Rislone is the street bottle: real MMT at the highest concentrate allowed for street use, for unleaded gasoline, ethanol E10, E15, E85 and racing fuel, and it states it will not harm catalytic converters or oxygen sensors. K&N states the same catalytic converter and oxygen sensor safety. Lucas goes the other way: designed for engines and vehicles not equipped with emissions aftertreatment systems, so it does not fit a modern emissions-equipped car. STP fits all gasoline engines, including cap-less gas systems.

Cap-less tanks and the pour routine

Cap-less tanks need a bottle that fits the filler. STP states compatibility with all gasoline engines, including cap-less gas systems, and Rislone states its bottle works in standard, obstructed and capless systems. The pour routine is simple where stated: STP says pour the entire contents in before or after fueling, and use the additive regularly at every fill-up. For injector cleaning alongside the boost, see the fuel injector cleaner guide.

Garage Fit Check

• Space: the Lucas pack measures 10.5 x 10.4 x 7.8 inches and weighs 12 pounds, while the Rislone pack measures 7 x 6 x 10 inches and weighs 4.78 pounds.
• Storage: STP bottles are 5.25 fl oz in a 12 pack, Rislone bottles 6 fl oz in a 12 pack, and BOOSTane a single 32 oz bottle.
• Check the tank: Rislone treats up to 20 gallons, K&N up to 18, STP up to 15; BOOSTane and Lucas state no treat volume.
• Check the vehicle: BOOSTane is not street-legal, Lucas is for vehicles without emissions aftertreatment systems, and Rislone and K&N state safe use on catalytic converters and oxygen sensors.

FAQ: garage tools

When should I use an octane booster?

When knock or ping shows up, or the fuel quality is suspect. Lucas targets knocks in high compression engines, Rislone knock and pings from low quality fuel, and STP knocking and pinging from combustion chamber deposits. A bottle does not replace repairs: if knock stays after a bottle, the engine needs a shop, not another bottle.

How much octane booster should I use?

Use the bottle’s stated treat volume. STP states one 5.25 fl oz bottle treats up to 15 gallons, Rislone one bottle treats up to 20 gallons, and K&N a 16 oz bottle treats up to 18 gallons. BOOSTane and Lucas state no treat volume, so follow the bottle rather than guessing an amount.

Is octane booster safe for catalytic converters?

It depends on the bottle. Rislone states it will not harm catalytic converters or oxygen sensors, and K&N states safe use on them. Lucas is designed for vehicles not equipped with emissions aftertreatment systems, so it is not the bottle for a converter-equipped car. BOOSTane is racing-only and not street-legal.

Does octane booster clean anything?

Some listings pair boost with cleaning. STP is a 2-in-1 additive that boosts octane and cleans the fuel intake system, with MMT plus Synthetic Technology; K&N cleans fuel injectors while boosting octane. Rislone rates its own fit as Best for dirty injectors, dirty valves and combustion chamber deposits in its spec table. BOOSTane and Lucas make no cleaning claim.

Is the racing booster street-legal?

No. BOOSTane states its Professional booster is not street-legal and is engineered for racing. For street cars, pick a bottle that states street use, such as Rislone with its street-use MMT concentrate.

Related: engine and shop equipment guides and fuel stabilizer for cars.