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Car Additives & Flushes

Opie Oils stocks a wide range of car additives and flushes designed to maintain performance, improve efficiency, and support long-term engine health. From fuel system cleaners and injector treatments to oil flushes and cooling system additives, our range covers key maintenance products for petrol and diesel vehicles. Browse the full range below, with free UK delivery on orders over £80.

Please note that fuel treatments cannot currently be shipped outside the UK.

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238 Products (Viewing: 1 - 60 of 238)

Liqui Moly Pro-Line Engine Flush
Opie Price
£12.95
Price Beater
Liqui Moly Engine Flush Plus

300ml - SKU 8374

Opie Price
£10.99
Price Beater
Millers Oils Engine Flush Fully Synthetic Engine Oil Treatment
Liqui Moly Hydraulic Lifter Additive

300ml - SKU 2770

Opie Price
£7.99
Price Beater
Classic Valvemaster PLUS 3-in-1 Lead Replacement Additive
Millers Oils CVL Extra Competition Valve Lubricant - High Octane Booster
Liqui Moly Cera Tec

300ml - SKU 3721

Opie Price
£27.95
Price Beater
Liqui Moly DPF / GPF Cleaner

400ml Aerosol - SKU 21942

Opie Price
£20.95
Price Beater
Liqui Moly DEF Anti Crystal Additive Concentrate
Classic Valvemaster Lead Replacement Additive
Millers Oils VSPe Power Plus One Shot (Ethanol / Lead / Octane) Fuel Treatment
Amsoil Diesel Cetane Boost

16oz Bottle (473ml)

RRP £11.82
£11.50
Price Beater
Millers Oils Diesel Power ECOMAX Fuel Treatment Multishot
Liqui Moly Octane Booster

200ml - SKU 21616

Opie Price
£13.99
Price Beater
Millers Oils VSPe Power Plus Multi-Shot (Ethanol / Lead / Octane) Fuel Treatment
Millers Oils Tank Safe Petrol Additive Fuel System Protection
Millers Oils Petrol Power ECOMAX Fuel Treatment Multishot
Wynns Engine Flush for Petrol & Diesel Engines - Detergent Based (51265)
Valvoline Diesel System Protector
Classic Etha-Guard Plus Ethanol Stabiliser Petrol Additive
Liqui Moly Motor Oil Saver

300ml - SKU 1802

Opie Price
£11.95
Price Beater
Millers Oils Petrol Power ECOMAX Fuel Treatment - One Shot Boost
Millers Oils Diesel Power ECOMAX One Shot Boost
Silkolene PRO BOOST Octane Improver (Fuchs)
Castrol Engine Shampoo (Pre-Oil Change Treatment)
Millers Oils Diesel Particulate Filter (DPF) Cleaner & Regenerator
Holts Speedflush Cooling System Cleaner - 250ml (RK1R)
Amsoil Performance Improver Gasoline Additive
Millers Oils Stop Leak Engine and Gear Oil Treatment
Wynns Dry Fuel - Water Remover for Petrol and Diesel Cars (71851)
Wynns Crystal Clean And Protect
Opie Price
£6.50
Price Beater
Liqui Moly Oil Smoke Stop

300ml - SKU 8901

Opie Price
£8.95
Price Beater
Liqui Moly Super Diesel Additive

250ml - SKU 1806

Opie Price
£9.95
Price Beater
Liqui Moly Mtx Carburetor + Valve Cleaner
Liqui Moly Radiator Cleaner

300ml - SKU 1804

Opie Price
£7.99
Price Beater
Liqui Moly Diesel Particulate Filter Protector
Liqui Moly Speed Tec Diesel Fuel Additive
Liqui Moly Fuel System Treatment

300ml - SKU 8365

Opie Price
£10.99
Price Beater
Liqui Moly Engine Flush
Liqui Moly Radiator Stop Leak
Opie Price
£7.99
Price Beater
Millers Oils EPS Ethanol Protection System Fuel Treatment Additive - One Shot
Clearance
Was £69.95
£24.95
Price Beater
Millers Oils EPP Petrol System Clean & Protect Fuel Treatment
Millers Oils EPP Diesel Injector Cleaner
Millers Oils EPP PPF Turbo & Exhaust Cleaner
Liqui Moly Oil Additive

300ml - SKU 2591

Opie Price
£9.95
Price Beater
Holts EGR & Carb Cleaner Aerosol - 500ml Aerosol (HMTN0201A)
Lucas Oil Engine Oil Stop Leak
Opie Price
£39.95
Price Beater
Lucas Oil Heavy Duty Oil Stabiliser
Opie Price
£11.95
Price Beater
Motul Fuel System Clean Auto - Car & Boat Fuel System Cleaner Additive
VP Racing Octanium Unleaded Octane Improver
Comma Diesel D-Tox Fuel System & Injector Cleaner
CE-LIT Rapid Radiator Leak Sealant - 0.3L (977)
Wynns Diesel Turbo Cleaner (31563B)
Wynns Air Intake, Carburettor & Throttle Valve Cleaner (54179)
Millers Oils Petrol Injector Cleaner
Motul Diesel System Clean Auto - Injector & Fuel System Cleaner
RED LINE Fuel System Additive - Water & Antifreeze / Coolant Remover - Concentrate
Millers Oils Extra Cool (Corrosion Inhibitor & Coolant Enhancer) Concentrate
Millers Oils CVL (Valve Seat Lubricant & Combustion Enhancer)
Motul Valve Expert - Petrol Lead Replacement Fuel Additive

Vehicle additives and flushes are designed to clean and protect different areas of your car’s engine and fuel system. Over time, deposits, carbon build-up and contaminants can affect performance and increase wear. Using the right treatment helps restore cleaner operation and supports smoother running.

Modern flushes are not like the aggressive older type ones that used solvents. The newer ones use detergents, antioxidants and pH neutralisers to clean the engine, while also improving the quality of any oil that doesn’t drain out.

Need an additive for diesel cars? We stock a variety of diesel additives and cetane boosters, along with DPF and EGR cleaners to help maintain emissions systems and reduce blockages. Petrol drivers can benefit from octane boosters and fuel additives, designed to enhance performance and support smoother engine response.

If you need help choosing the right additives for your vehicle, feel free to contact us — we’re happy to help. We can advise you on other automotive oils and fluids too, from engine oil to gearbox oil.

Browse car flushes and additives at Opie Oils today and help keep your vehicle running cleanly, efficiently, and reliably, with no-leak guarantee on every order.