Forte Advanced Formula Motor Flush: every question customers actually ask

Forte Advanced Formula Motor Flush is a £15 engine cleaner that goes into the old oil for 15 to 20 minutes before an oil change to loosen sludge, varnish and carbon so they drain out with the oil instead of staying in the engine. It is for petrol and diesel engines including hybrids, DPF and start-stop cars, but it is not for wet-belt (TBIO) engines such as the Ford EcoBoost, PSA PureTech and small VW Group TSI and TDI units, which need Forte New Generation Engine Flush instead.

By Phil Clements, BMW Tool RentalUpdated 16 September 2026

What is it and what does it fix?

An internal engine clean done at the oil change, so the muck leaves with the old oil.

Advanced Formula Motor Flush is a blend of cleaning agents, dispersants and anti-wear agents that is added to the old engine oil immediately before it is drained. Idling for 15 to 20 minutes lets it break down and suspend the sludge, carbon, varnish and lacquer that build up in the crankcase and the oil pick-up pipe, so that contamination drains away with the old oil rather than sitting in the block and dirtying the fresh oil.

The symptoms it is aimed at are the ones sludge causes: sticking piston rings and the oil burning that follows, noisy hydraulic lifters (ticking or tapping), sticking VVT units, hunting on idle and excessive oil consumption. The one fault code Forte associate with it is contamination-related, P1341 (camshaft adjustment, bank 1) on a VVT system gummed up by dirty oil.

Used at every service it frees sticking rings, unclogs lifters, restores VVT operation, removes moisture and stabilises compression. Just as important, it leaves a clean baseline so follow-on treatments such as Oil Fortifier and Seal Conditioner work without sludge in the way. Reviews and the order button are on the Advanced Formula Motor Flush product page. It is often used alongside Forte New Generation Engine Flush; the Forte New Generation Engine Flush page explains when that pairing makes sense.

How do I use it?

Forte's instructions, in order. It is a 20-minute job that sits inside a normal oil change.

Check your engine is not a wet-belt designIf the timing belt runs in the oil (Ford EcoBoost, Ford 1.5 and 1.6 TDCi, VW Group 1.0, 1.2 and 1.4 TSI and TDI, PSA 1.2 PureTech), stop here and use New Generation Engine Flush instead.
Add one bottle to the old engine oilThrough the filler cap, with the old oil still in the engine, immediately before the oil change.
Idle at normal operating temperature for 15 to 20 minutesDo not drive it. Let the engine tick over warm so the flush circulates and loosens the deposits.
Drain the oil and replace the filterThe suspended sludge, varnish and moisture leave with the old oil. Always fit a new filter, because the old one has caught what the flush loosened.
Refill with fresh oil, and add Oil Fortifier if the engine is wornForte's best practice for a high-mileage engine is a flush, then fresh oil, then Oil Fortifier into the new oil. Repeat the flush at every routine service.

When will it not help?

A flush cleans. It does not repair. These are the cases where it is the wrong bottle or only half the answer.

Wet-belt (TBIO) engines. Advanced Formula Motor Flush is not suitable for engines whose timing belt runs in oil. Forte make a separate wet-belt-safe product, New Generation Engine Flush (£17), and that is the one to buy for a 1.0 EcoBoost, 1.2 PureTech or small TSI.
Worn parts. It frees rings that are stuck in carbon and lifters that are clogged with sludge. It cannot restore rings that are worn out, a lifter that has collapsed mechanically or a VVT unit that has failed. If a flush does not change the noise, the part needs looking at.
A leak that sludge was hiding. The flush does not cause leaks, but if sludge was temporarily plugging a worn or cracked seal, removing it can reveal a leak that was already there. That seal needed attention anyway; Seal Conditioner can help if the rubber has hardened rather than split.
Oil that is not being changed. It is designed to be drained out with the old oil after 15 to 20 minutes. It is not a top-up treatment to leave in the sump between services.

Forte Advanced Formula Motor Flush

The pre-oil-change engine flush for sludge, sticking rings, noisy lifters and sticking VVT. One bottle in the old oil, 15 to 20 minutes idling, drain and fit a new filter. Not for wet-belt engines. 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.

£15Free UK delivery on £35+ orders

Order Motor Flush Full product page

Forte New Generation Engine Flush

The wet-belt-safe flush. Same 15 to 20 minute pre-oil-change clean, formulated as safe for TBIO engines such as the Ford 1.0 EcoBoost, PSA 1.2 PureTech and VW Group 1.0 to 1.4 TSI and TDI. Choose this one if your belt runs in oil. 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.

£17Free UK delivery on £35+ orders

Order New Generation Flush Full product page

Motor Flush questions, in the order people ask them

My engine ticks on a cold start. Will an engine flush fix noisy lifters?

If the lifter is clogged with sludge or varnish, yes, that is what the flush is for: it unclogs hydraulic lifters so they pump up properly again. If the lifter has worn or collapsed mechanically, no flush will fix it. Do the flush at the oil change and judge the noise afterwards; the noisy lifters page covers what to check next.

What are the symptoms of sludge in an engine?

Ticking lifters, hunting at idle, rising oil consumption from rings stuck in carbon, a VVT rattle or a P1341 code, and thick black deposits under the filler cap. Motor Flush is designed to break down and suspend that sludge so it drains out with the old oil.

I have a P1341 fault code. Can a flush clear it?

P1341 is a camshaft adjustment (VVT, bank 1) code, and Forte associate it with contamination: dirty oil gumming up the VVT unit. If that is the cause, flushing at the oil change restores VVT operation and the code stops returning. If the code comes back on clean oil, the VVT solenoid or unit needs diagnosing.

Does Forte Engine Flush actually work?

It does what a flush can do: loosen sludge, varnish and carbon in 15 to 20 minutes of idling so they leave with the old oil, freeing stuck rings and clogged lifters and restoring VVT operation. It will not rebuild worn parts. Customer reviews are on the product page.

What are the Forte Engine Flush instructions?

Add one bottle to the old oil, idle at normal operating temperature for 15 to 20 minutes without driving, then drain the oil and fit a new filter. Refill with fresh oil. Forte recommend it at every routine service.

Can I drive with the flush in the oil?

No. It is an idle-only product: 15 to 20 minutes ticking over warm, then drain. It is not formulated to stay in the sump under load.

Do I need a new oil filter after flushing?

Yes. The old filter has caught what the flush loosened. Forte's instruction is to drain the oil and replace the filter as part of the same job.

Does the engine need to be warm?

Yes. Add the bottle and idle at normal operating temperature so the flush circulates through hot oil. A cold engine at idle will not reach every passage in 15 to 20 minutes.

How often should I use Motor Flush?

Forte recommend it at every routine service, so once per oil change. That keeps the engine clean rather than letting sludge build up for years and trying to shift it in one go.

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

No. Advanced Formula Motor Flush is not suitable for wet-belt (TBIO) engines. Forte make New Generation Engine Flush for those, and it is the one to buy for a Ford EcoBoost, Ford 1.5 or 1.6 TDCi, VW Group 1.0, 1.2 or 1.4 TSI and TDI, or a PSA 1.2 PureTech. Full explanation on the wet-belt engine flush page.

What is the difference between Advanced Formula Motor Flush and New Generation Engine Flush?

Both are 15 to 20 minute pre-oil-change flushes for sludge, sticking rings, noisy lifters and VVT problems. The key difference is that New Generation Engine Flush is formulated as safe for wet-belt engines and Advanced Formula Motor Flush is not. If your belt runs in the oil, buy New Generation. If it does not, either does the job and Motor Flush is £15 against £17.

Is it safe for a diesel with a DPF?

Yes. Forte list it as safe for petrol and diesel engines, including hybrids, DPF-equipped cars and start-stop systems. The flush leaves with the old oil, so nothing reaches the DPF.

Can I use it on a BMW?

Yes, on any BMW petrol or diesel that does not have a wet belt; the wet-belt engines Forte name are Ford, VW Group and PSA units. A VVT (VANOS) unit sticking on dirty oil is the contamination-related problem Forte list it for, and it is safe with a DPF and start-stop.

Will an engine flush cause leaks?

The flush itself does not cause leaks. What can happen is that sludge was temporarily plugging a worn or cracked seal, and once the sludge is gone the leak shows. That seal was already failing. If the rubber has hardened rather than split, Forte Seal Conditioner in the fresh oil can condition it.

Is it safe for an old, high-mileage engine that has never been flushed?

That is the engine it is designed for, and the risk people worry about is the hidden-leak point above. Do the flush, change the oil and filter, then add Oil Fortifier to the fresh oil; that is Forte's sequence for a worn engine.

Can I use it in a petrol car?

Yes. It is for petrol and diesel engines alike, and the petrol GDI engines that carbon up are good candidates. Pair it with Forte Advanced Formula Petrol Treatment in the tank if you want the fuel side cleaned at the same service.

Should I use Motor Flush before Oil Fortifier or Seal Conditioner?

Yes. Forte's best practice is flush first, so the follow-on treatments go into clean oil and work without sludge interference. Flush at the oil change, then Oil Fortifier into the fresh oil, then Seal Conditioner a day later if you are treating valve seal smoke.

Does it clean the oil pick-up pipe?

Sludge in the crankcase and oil pick-up pipe is exactly what Forte list it for. A blocked pick-up starves the pump, so a flush at each service is cheaper than the low-pressure damage that follows.

How much does an engine flush cost?

The bottle is £15 with free UK delivery on orders of £35 or more, and it adds about 20 minutes to an oil change you were doing anyway. A garage charges labour for the same idle-and-drain, so most customers do it themselves at the service.

Where can I buy Forte Motor Flush in the UK?

From BMW Tool Rental's Advanced Formula Motor Flush page, £15 with free UK delivery on orders of £35 or more, 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.