22 Products
Your Current Vehicle
Or
Select Your Vehicle
A tank additive modifies fuel, not failed hardware
Retail petrol already contains a refinery and terminal additive package. Supplementary treatment adds chemistry for a specific condition, so its value depends on the starting fuel, concentration, engine and operating cycle.
Use evidence to match the function. A deposit-control product cannot restore a leaking injector seat or cracked ignition coil.
Main petrol-additive categories
| Type | Intended function | Appropriate context | Limitation |
|---|---|---|---|
| Injector detergent | Controls deposits in fuel-wetted passages/tips. | Compatible maintenance or deposit diagnosis. | Does not repair wear or electrical faults. |
| Octane improver | Raises knock resistance by a stated amount. | Where engine and product permit. | Cannot correct overheating or carbon hot spots. |
| Fuel stabiliser | Slows oxidation during storage. | Added to fresh fuel before lay-up. | Cannot reverse severe degradation. |
| Corrosion protection | Helps protect fuel-system metals. | Storage and ethanol-containing fuel as approved. | Cannot repair rusted tanks/lines. |
| Water-management product | Handles limited moisture by defined chemistry. | Only where manufacturer/product approves. | Not for bulk water contamination. |
| Valve/combustion cleaner | Targets deposits through specified delivery route. | Professional or tank method as designed. | Tank dose cannot reach every surface. |
Identify the fuel system
Port and direct injection expose different surfaces
Port injectors spray upstream of intake valves, so detergent fuel washes valve backs. Direct injectors spray into the cylinder; fuel does not normally contact intake-valve deposits caused by oil mist and EGR.
A treatment claiming universal intake cleaning needs scrutiny. Severe direct-injection deposits may require inspected mechanical or specialist chemical service.
Compatibility checklist
| Check | Why it varies | Evidence |
|---|---|---|
| Fuel grade | Octane and ethanol content differ. | Pump label, vehicle and product instructions. |
| Injection | Port, direct and mixed systems. | Explicit system compatibility. |
| After-treatment | Catalyst, oxygen sensor and GPF sensitivity. | Low-ash/non-harm statement. |
| Engine demand | Compression, boost and calibration. | Required minimum octane. |
| Dose | Container may treat different tank volumes. | Measured ratio, not whole-bottle assumption. |
| Storage | Fuel age, temperature and tank material. | Stabiliser timing and shelf-life directions. |
| Restrictions | Manufacturer may prohibit supplementary additives. | Current service/owner guidance. |
Diagnose common symptoms first
| Symptom | Deposit possibility | Other priority checks | Urgency |
|---|---|---|---|
| Cold hesitation | Injector or intake deposit. | Fuel pressure, temperature data and ignition. | Prompt. |
| Misfire under load | Poor injector flow possible. | Coils, plugs, compression and lean mixture. | Stop if warning flashes. |
| Knock/pinging | Octane or chamber deposit. | Wrong fuel, overheating, boost and timing. | Immediate under heavy knock. |
| Poor economy | Spray quality may contribute. | Driving, tyres, thermostat, sensors and leaks. | Diagnose. |
| Hard hot start | Leaking injector. | Pressure decay, purge valve and sensor data. | High. |
| High emissions | Mixture/deposit issue. | Catalyst, oxygen sensors, misfire and oil use. | Prompt. |
Injector detergents
Suitable detergents can prevent or remove certain deposits on injector tips and fuel-wetted components. Improvement depends on chemistry, dose and deposit type. Mechanically eroded holes, stuck electrical actuators and internal leakage require component diagnosis.
Use fuel trims, balance tests, pressure and injector current/flow evidence rather than judging only by exhaust note.
Octane and knock control
Octane rating measures resistance to auto-ignition under test conditions. A knock-controlled engine may adjust timing to available fuel, but it cannot always exploit a higher rating for more output. Always meet the vehicle's minimum grade first.
Product claims may state points differently: one “point” can mean a tenth of an octane number in some marketing. Read the actual treated-fuel result rather than assuming a large increase.
Knock is not always low octane
Overheating, excessive boost, lean mixture, wrong spark plugs, carbon hot spots and sensor/control faults can cause abnormal combustion. Severe knock damages pistons and rings.
Do not mask persistent knock with repeated improver. Read codes and verify fuel grade, cooling and calibration.
Ethanol-containing petrol
Ethanol absorbs moisture and changes material compatibility. Modern compatible vehicles are designed for specified blends, but older fuel hoses, seals and tanks may need assessment. An additive cannot make an incompatible component suitable.
Bulk water can phase-separate and settle. Do not attempt to disperse a contaminated tank without a controlled recovery plan.
Fuel storage and oxidation
Petrol loses volatile components and oxidises, forming gums. Add stabiliser to fresh fuel before storage, circulate it safely through the system where instructions require and manage tank level/ventilation according to vehicle storage guidance.
A sour smell, dark fuel or persistent poor running after long storage warrants sampling and safe disposal, not a stronger stabiliser dose.
Volatility and the evaporative-emissions system
Petrol must vaporise for starting yet remain contained in the tank and EVAP system. A loose cap, purge valve stuck open, saturated charcoal canister or leaking vapour pipe can cause odour, hard starting and mixture faults that additive will not correct.
Do not deliberately vent a tank or overfill after the pump nozzle stops. Liquid fuel entering the carbon canister can damage it. Diagnose EVAP leaks with approved low-pressure smoke equipment and fire-safe procedures.
Accurate dosing
| Stage | Correct practice | Error prevented |
|---|---|---|
| Estimate fuel | Use actual tank quantity. | Unknown concentration. |
| Calculate | Apply stated millilitres per litre. | Whole-bottle overdose. |
| Measure | Use clean fuel-compatible graduated tool. | Contamination and spills. |
| Add | Follow before/after refuelling sequence. | Poor mixing. |
| Record | Note batch, amount, litres and mileage. | Accidental repeat dosing. |
| Assess | Compare codes/data over defined usage. | Subjective attribution. |
Catalyst and particulate-filter compatibility
Metal-containing octane improvers or ash-forming ingredients can leave residues in oxygen sensors, catalysts and petrol particulate filters. Use only explicitly compatible products at the correct dose.
A flashing engine lamp indicates catalyst-damaging misfire; stop rather than attempting to clean through it.
Professional induction cleaning
Products introduced through the intake require controlled delivery to prevent hydrolock, runaway speed, sensor damage and catalyst overheating. They are not poured through a vacuum hose by guesswork.
Inspect deposit severity and follow a validated system. Mechanical walnut-shell or other cleaning also needs valve closure confirmation and complete media recovery.
Handling and fire safety
Petrol additives may be flammable and harmful. Work outdoors or with suitable ventilation, extinguish ignition sources and avoid static-producing transfers. Wear the stated eye and skin protection.
Keep in the original labelled container, secured away from children, heat and food. Never transfer to a drinks bottle.
Wrong-fuel and bulk contamination
Do not use additive to correct diesel, AdBlue, coolant or bulk water in a petrol tank. Do not start the engine; arrange specialist drain and system assessment based on whether pumps operated.
Improvised solvents can attack seals, reduce octane or change combustion unpredictably.
Monitoring after treatment
| Evidence | Before | After |
|---|---|---|
| Fault status | Save codes and freeze frame. | Complete monitors and rescan. |
| Fuel trims | Record hot idle and controlled load. | Compare under same conditions. |
| Misfire counts | Identify cylinder and operating range. | Confirm no catalyst-risk recurrence. |
| Starting | Measure crank time hot/cold. | Repeat at comparable temperature. |
| Fuel economy | Use several comparable brim-to-brim cycles. | Avoid dashboard-only conclusion. |
| Oil condition | Check level and fuel dilution. | Investigate rising level promptly. |
Common mistakes
Do not combine cleaners, add a whole bottle to a nearly empty tank without instruction, pour petrol treatment into AdBlue or oil, clear codes before saving evidence or assume premium fuel and octane booster are equivalent.
More solvent is not a faster repair. Over-concentration can reduce lubricity or alter seals and combustion.
UK emissions and road use
Additives do not legalise removal of catalysts, GPFs or warning systems. A vehicle must meet applicable emissions and remain free from dangerous fuel leakage and excessive smoke.
Test only within normal legal road use. Do not drive aggressively to “burn through” a flashing warning or severe knock.
Practical petrol-additive FAQs
Q: Can cleaner repair a failed injector?
A: No. It may address suitable deposits, not mechanical/electrical failure.
Q: Does tank cleaner wash direct-injection intake valves?
A: Normally no, because fuel is injected after those valves.
Q: Does higher octane always add power?
A: No. The engine must be calibrated to use it.
Q: Can octane booster stop all knock?
A: No. Cooling, mixture, boost and mechanical faults also cause knock.
Q: Can two additives be mixed?
A: Only where combined compatibility and dosing are explicit.
Q: Will stabiliser restore stale petrol?
A: No. It is most effective when added to fresh fuel before storage.
Q: Can additive remove bulk water?
A: No. Contaminated fuel requires safe sampling and recovery.
Q: Is petrol additive safe for a GPF?
A: Use only a product explicitly compatible with the vehicle's after-treatment.
Q: Is more cleaner more effective?
A: No. Measure the stated concentration.
Q: Can petrol treatment go in the oil?
A: No, unless an entirely separate product explicitly specifies that use.
Q: Should codes be cleared before treatment?
A: Save them and their freeze-frame evidence first.
Q: Can a flashing engine lamp be driven through?
A: No. Active misfire can damage the catalyst.
Q: How should improvement be judged?
A: Compare defined symptoms and live data under repeatable conditions.
