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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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226 Products (Viewing: 1 - 60 of 226)

Liqui Moly Pro-Line Engine Flush
Opie Price
£11.95
Price Beater
Liqui Moly Engine Flush Plus

300ml - SKU 8374

Opie Price
£9.95
Price Beater
Liqui Moly Cera Tec

300ml - SKU 3721

Opie Price
£24.95
Price Beater
Millers Oils Engine Flush Fully Synthetic Engine Oil Treatment
Liqui Moly Hydraulic Lifter Additive

300ml - SKU 2770

Opie Price
£6.95
Price Beater
Millers Oils VSPe Power Plus One Shot (Ethanol / Lead / Octane) Fuel Treatment
Millers Oils Extra Cool (Corrosion Inhibitor & Coolant Enhancer) Concentrate
Millers Oils Diesel Injector Cleaner
Amsoil Diesel Cetane Boost

16oz Bottle (473ml)

Opie Price
£16.99
Price Beater
Liqui Moly Motor Oil Saver

300ml - SKU 1802

Opie Price
£10.99
Price Beater
Liqui Moly DPF / GPF Cleaner

400ml Aerosol - SKU 21942

Opie Price
£18.95
Price Beater
VP Racing Octanium Octane Improver

1 Quart (946ml)

RRP £25.00
£24.95
Price Beater
STP Complete Diesel Fuel System Cleaner - 400ml (65400EN)
Wynns Extreme Cooling System Degreaser (25541)
Millers Oils Stop Leak Engine and Gear Oil Treatment
Millers Oils Diesel Power ECOMAX Fuel Treatment Multishot
RED LINE 85 PLUS Diesel Enhancer
Classic Valvemaster Lead Replacement Additive
Liqui Moly DEF Anti Crystal Additive Concentrate
Liqui Moly Mtx Carburetor + Valve Cleaner
Liqui Moly Radiator Stop Leak
Opie Price
£6.95
Price Beater
Liqui Moly Oil Additive

300ml - SKU 2591

Opie Price
£8.95
Price Beater
Millers Oils Petrol Power ECOMAX Fuel Treatment Multishot
Millers Oils Diesel Particulate Filter (DPF) Cleaner & Regenerator
Amsoil Performance Improver Gasoline Additive
Comma X-Flow Flush Out Mineral Engine Oil Flush
Millers Oils EPS Ethanol Protection System Fuel Treatment Additive - One Shot
Clearance
Was £69.95
£24.95
Price Beater
Wynns Engine Flush for Petrol & Diesel Engines - Detergent Based (51265)
Millers Oils VSPe Power Plus Multi-Shot (Ethanol / Lead / Octane) Fuel Treatment
Millers Oils CVL (Valve Seat Lubricant & Combustion Enhancer)
Motul MoCool Car & Motorcycle Coolant Additive - Concentrate
Liqui Moly Fuel System Treatment

300ml - SKU 8365

Opie Price
£9.95
Price Beater
Millers Oils EPP Diesel System Clean & Protect Fuel Treatment
Millers Oils EPP Engine Flush Fully Synthetic Engine Oil Treatment
Liqui Moly Octane Booster

200ml - SKU 21616

Opie Price
£11.95
Price Beater
Classic Etha-Guard Plus Ethanol Stabiliser Petrol Additive
Liqui Moly Oil Smoke Stop

300ml - SKU 8901

Opie Price
£7.99
Price Beater
Liqui Moly Radiator Cleaner

300ml - SKU 1804

Opie Price
£6.95
Price Beater
Classic Valvemaster PLUS 3-in-1 Lead Replacement Additive
Millers Oils Diesel Power ECOMAX One Shot Boost
Valvoline Petrol System Cleaner V1
Wynns Catalytic Converter & Lambda Cleaner (24463)
Wynns Radiator Flush (56064)
Valvoline Cooling System Cleaner
Wynns Hydraulic Valve Lifter Concentrate (76844)
VP Racing Octanium Unleaded Octane Improver
Wynns DPF & GPF On Car Cleaner (29079B)
KALIMEX JLM Diesel Injector Cleaner - 250ml (J02320)
Wynns Diesel Total Action Treatment (33092C)
Comma Diesel D-Tox Fuel System & Injector Cleaner
CE-LIT Rapid Radiator Leak Sealant - 0.3L (977)
Millers Oils Petrol Injector Cleaner
Millers Oils Tank Safe Petrol Additive Fuel System Protection
Castrol Engine Shampoo (Pre-Oil Change Treatment)
Millers Oils Petrol Power ECOMAX Fuel Treatment - One Shot Boost
Millers Oils CVL Extra Competition Valve Lubricant - High Octane Booster
Silkolene PRO BOOST Octane Improver (Fuchs)
Silkolene PRO CCA Ultra Cooling System Corrosion Inhibitor
Wynns Crystal Clean And Protect
Opie Price
£6.50
Price Beater
Liqui Moly Power Steering Oil Leak Stop

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.