Forte Advanced Formula Petrol Treatment: every question customers actually ask

Forte Advanced Formula Petrol Treatment is a £20 fuel system cleaner for petrol engines that are idling rough, hesitating, misfiring or down on power because of carbon and deposits on the injectors, inlet valves and combustion chamber. It is for any petrol car including direct injection, hybrid and wet-belt engines on fuel up to E20; it is not for diesels, and it will not cure a fault caused by a failed part, a sensor or the ignition system.

By Phil Clements, BMW Tool RentalUpdated 16 September 2026

What is it and what does it fix?

A whole-fuel-system clean from the tank to the catalyst, one bottle per service.

Advanced Formula Petrol Treatment is a petrol fuel treatment that removes deposits from the injectors, intake valves and combustion areas and then protects the system. Forte list ten components it cleans in turn: the fuel tank, fuel pump, injectors, inlet valves, combustion chamber, exhaust valves, piston rings, lambda sensor, EGR valve and the GPF or catalyst. Alongside the cleaning it controls fuel oxidation so gum, varnish and acid do not form, and it prevents corrosion in the fuel system.

The symptoms it is aimed at are the ones carbon causes on a petrol engine: rough idling, hesitation when accelerating, misfires, reduced power and higher emissions. Direct injection (GDI) engines are the classic case because deposits build on their inlet valves. Forte also position it against low speed pre-ignition (LSPI), the damaging knock event modern turbocharged direct-injection engines can suffer. It is a preventative treatment, so it is not tied to any particular fault code.

It also lubricates. Forte list upper cylinder lubrication, keeping injector spray patterns correct, freeing sticking compression rings and keeping the EGR valve, lambda sensor and catalyst clean among its benefits. Reviews and the order button are on the Advanced Formula Petrol Treatment product page.

How do I use it?

One bottle, one full tank, nothing to fit.

Fill the tankForte's dose is one complete bottle to a full tank of petrol, so fill up first or pour it in at the pump before you fill.
Add the whole bottlePour it into the filler neck. Do not split the bottle across two tanks; the concentration is set for one full tank.
Drive normally until the tank is usedThe treatment works as the fuel passes through the pump, injectors and combustion chamber. A mix of town and open-road driving over the tank is ideal.
Clean the oil side at the same serviceForte recommend pairing it with Advanced Formula Motor Flush in the old oil before the change, so the fuel system and the oil system are cleaned together.
Repeat at every routine serviceIt is a preventative treatment. One bottle per service keeps deposits from rebuilding rather than trying to shift years of carbon in one go.

When will it not help?

It cleans deposits. It does not replace parts or diagnose faults. Save the £20 in these cases.

Diesel engines. This is a petrol formulation. A diesel with the same symptoms wants Forte Advanced Formula Diesel Treatment, and a diesel MOT emissions fail wants Diesel Emissions Reducer.
A misfire from a failed part. A dead coil pack, a worn spark plug, a split vacuum hose, a faulty sensor or low compression will misfire whether the injectors are clean or not. Mechanical, ignition, sensor and failed-component faults need separate diagnosis; the treatment is not a substitute for it.
A petrol MOT emissions fail on its own. This is the maintenance cleaner. For a failed CO or HC reading and a catalyst that needs cleaning before a retest, Forte make Petrol Emissions Reducer, covered on the petrol MOT emissions page.
Expecting an instant fix. It works over the tank as fuel passes through the system. If the idle is no better once the treated tank is used, the cause is not deposits.

Forte Advanced Formula Petrol Treatment

The petrol fuel system cleaner for rough idle, hesitation and carbon on injectors and inlet valves. One bottle to a full tank at every service; cleans ten components from the tank to the catalyst. Safe for direct injection, hybrid and wet-belt engines on fuel up to E20. Ships worldwide from the UK; UK delivery free on orders of £35 or more, postage and any duty shown at checkout for the USA, Canada, Australia, New Zealand and Ireland.

£20Free UK delivery on £35+ orders

Order Petrol Treatment Full product page

Petrol Treatment questions, in the order people ask them

My petrol car idles rough and hesitates when I accelerate. Will this fix it?

If the cause is carbon or deposits on the injectors, inlet valves or combustion chamber, that is what the treatment is for: rough idling, hesitation, misfires and reduced power from build-up. If the cause is a coil, plug, sensor or air leak, cleaning the fuel system will not change it. One tank tells you which.

Does it work as a petrol injector cleaner?

Yes. Injectors are one of the ten components Forte list it cleaning, and maintaining the injector spray pattern is a stated benefit. It also cleans the pump and tank upstream of them, so dirt is not pushed straight back through.

Will it clean the carbon off the inlet valves on a direct injection engine?

Inlet valves are on Forte's list of what it cleans, and GDI inlet valve carbon is the specific problem the treatment is positioned against. It is fully compatible with high-pressure direct injection engines. Heavy, baked-on carbon on a neglected engine may still need a manual clean; a bottle at every service is how you avoid getting there.

Does it clean the catalytic converter?

The GPF or catalyst is the last of the ten components on Forte's list, and keeping the catalyst clean is a stated benefit. For an actual MOT emissions fail, though, Forte's dedicated product is Petrol Emissions Reducer; this bottle is the maintenance cleaner.

Will it help with an EGR valve or lambda sensor?

Both are on the list. Forte state it maintains the cleanliness of the EGR valve and the lambda (oxygen) sensor. A sensor that has failed electrically is a different matter and needs replacing.

What is low speed pre-ignition and does this prevent it?

LSPI is an early, uncontrolled ignition event at low revs and high load in modern turbocharged direct-injection engines, and it can damage pistons. Forte position this treatment as combating LSPI by keeping the combustion chamber free of the deposits that trigger it.

Does it improve fuel economy or power?

Forte's stated benefits are about restoring what deposits took away: correct spray patterns, cleaner combustion, freed compression rings and reduced emissions. If your car has lost power to carbon, cleaning it back brings that power back. It is not claimed as a performance additive on a clean engine.

How do I use Forte Petrol Treatment?

Add one complete bottle to a full tank of petrol and drive normally. Forte recommend it at every routine service, ideally alongside Advanced Formula Motor Flush so the oil system is cleaned at the same time. Full instructions on the product page.

Is one bottle enough, or do I need two?

One bottle to a full tank is Forte's dose. For a badly neglected engine, use it at consecutive fills rather than doubling the dose in one tank.

Can I put it in half a tank?

The dose is set for a full tank, so fill up. Adding it to half a tank makes the mix stronger than intended and shortens the cleaning period.

How long does it take to work?

It works as the treated fuel passes through the system, so over one tank of driving. Judge the idle and the hesitation once that tank is used, not after the first mile.

How often should I use it?

At every routine service. It is a preventative treatment designed to stop gum, varnish and carbon building between services, not a one-off rescue.

Is it safe for a hybrid?

Yes. Forte list it as fully compatible with hybrid engines as well as high-pressure direct injection.

Is it safe with E10 petrol?

Yes. It is safe with all petrol and bio-petrol blends up to E20, which covers UK E5 and E10.

Can I use it in a wet-belt engine like a 1.0 EcoBoost or 1.2 PureTech?

Yes. Forte explicitly verify it as safe for timing-belt-in-oil (wet-belt) engines. It goes in the fuel, not the oil. If you also want to flush the oil on a wet-belt engine, use New Generation Engine Flush, not Advanced Formula Motor Flush.

Can I use it in a diesel?

No. It is a petrol formulation. Forte make Advanced Formula Diesel Treatment for the diesel equivalent.

Is it the same as Forte Petrol Emissions Reducer?

No. Petrol Emissions Reducer is the product for a failed MOT emissions test and Forte state it contains polyetheramine (PEA); Forte do not make that claim for Advanced Formula Petrol Treatment, which is the routine-service fuel system cleaner. Pick by job: retest, Emissions Reducer; maintenance and rough running, Petrol Treatment.

Will it fix a misfire on my BMW N62?

Only if the misfire is coming from dirty injectors or combustion deposits, in which case a tank of treated fuel is a sensible, cheap first step. An N62 misfire can also be coils, plugs, valve seals fouling plugs or a vacuum leak, and the treatment does not diagnose those.

Does it stop my car from failing the petrol emissions test?

It reduces emissions caused by carbon build-up, which helps, but it is not the dedicated retest product. If you already have a failed CO or HC reading, read the petrol MOT emissions page and use Petrol Emissions Reducer.

Can I use it with Motor Flush at the same service?

Yes, and Forte recommend it. Petrol Treatment in the tank cleans the fuel side; Advanced Formula Motor Flush in the old oil for 15 to 20 minutes before the change cleans the oil side. Together they cover the whole engine.

How much is Forte Petrol Treatment and where do I buy it?

£20 with free UK delivery on orders of £35 or more from BMW Tool Rental's Petrol Treatment page, dispatched from Lichfield.

Do you deliver outside the UK?

Yes. UK delivery is free on orders of £35 or more. Orders to the USA, Canada, Australia, New Zealand, Ireland and the rest of Europe are sent tracked from the UK, with postage and any duty shown at checkout before you pay. There is a dedicated page for US customers.