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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. Read our complete guide to car additives for guidance on what product does what job!

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

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241 Products (Viewing: 1 - 60 of 241)

Liqui Moly Pro-Line Engine Flush
Opie Price
£10.99
Price Beater
Liqui Moly Engine Flush Plus

300ml - SKU 8374

Opie Price
£7.99
Price Beater
Millers Oils Diesel Power ECOMAX Fuel Treatment Multishot
Millers Oils Engine Flush Fully Synthetic Engine Oil Treatment
Millers Oils EPS Ethanol Protection System Fuel Treatment Additive - One Shot
Clearance
Was £69.95
£24.95
Price Beater
Millers Oils VSPe Power Plus Multi-Shot (Ethanol / Lead / Octane) Fuel Treatment
Liqui Moly Cera Tec

300ml - SKU 3721

Opie Price
£29.95
Price Beater
Classic Valvemaster PLUS 3-in-1 Lead Replacement Additive
Millers Oils Petrol Power ECOMAX Fuel Treatment Multishot
Classic Valvemaster Lead Replacement Additive
Millers Oils VSPe Power Plus One Shot (Ethanol / Lead / Octane) Fuel Treatment
Classic Etha-Guard Plus Ethanol Stabiliser Petrol Additive
Millers Oils EPP Engine Flush Fully Synthetic Engine Oil Treatment
Liqui Moly Hydraulic Lifter Additive

300ml - SKU 2770

Opie Price
£6.95
Price Beater
Millers Oils Diesel Particulate Filter (DPF) Cleaner & Regenerator
Motul MoCool Car & Motorcycle Coolant Additive - Concentrate
Millers Oils Tank Safe Petrol Additive Fuel System Protection
Liqui Moly Pro-Line Gasoline System Cleaner
Liqui Moly DEF Anti Crystal Additive Concentrate
Millers Oils CVL Extra Competition Valve Lubricant - High Octane Booster
Millers Oils Petrol Injector Cleaner
Millers Oils Stop Leak Engine and Gear Oil Treatment
Liqui Moly Injection Cleaner

300ml - SKU 1803

Opie Price
£9.95
Price Beater
Liqui Moly Pro-Line Radiator Stop Leak K
Liqui Moly Motor Oil Saver

300ml - SKU 1802

Opie Price
£8.95
Price Beater
Liqui Moly Mtx Carburetor + Valve Cleaner
Millers Oils EPP DPF Turbo & Exhaust Cleaner
Liqui Moly Oil Additive

300ml - SKU 2591

Opie Price
£7.99
Price Beater
Liqui Moly Pro-Line Diesel System Cleaner
Liqui Moly Diesel Purge
Opie Price
£17.95
Price Beater
Liqui Moly Radiator Stop Leak
Opie Price
£5.95
Price Beater
Liqui Moly DPF / GPF Cleaner

400ml Aerosol - SKU 21942

Opie Price
£15.95
Price Beater
Amsoil Performance Improver Gasoline Additive
Wynns Diesel Particulate Filter Cleaner (28263)
RED LINE 85 PLUS Diesel Enhancer
Wynns Hydraulic Valve Lifter Concentrate (76844)
Motul Fuel System Clean Auto - Car & Boat Fuel System Cleaner Additive
STP Oil Treatment for Petrol Engines - 450ml (60450EN06)
Cataclean Petrol Fuel And Exhaust System Cleaner - 500ml Bottle (CAT001)
Cataclean Diesel Fuel and Exhaust System Cleaner - 500ml Bottle (CAT002)
Lucas Oil Heavy Duty Oil Stabiliser
Opie Price
£12.50
Price Beater
KALIMEX JLM Diesel Rapid Fuel System Clean - 500ml (J02330)
Wynns CV Cooling System Flush (W45990)
Silkolene PRO FST Fuel System Treatment For Petrol Engines
Silkolene PRO BOOST Octane Improver (Fuchs)
RED LINE SI-1 Fuel System Cleaner
Millers Oils Petrol Power ECOMAX Fuel Treatment - One Shot Boost
VP Racing Madditive Diesel All-In-One
Valvoline Engine Oil Treatment ML V1
Wynns Xtreme Diesel System Clean - Powerful 'One Tank' Clean-Up (12264)
Amsoil DOMINATOR Octane Boost

12oz Bottle

RRP £11.56
£10.99
Price Beater
Amsoil Diesel Cetane Boost

16oz Bottle (473ml)

RRP £11.82
£11.50
Price Beater
Wynns Diesel Turbo Cleaner (31563B)
Comma Engine Flush Oil Additive for Petrol & Diesel Engines
Wynns Stop Smoke for Oil Petrol & Diesel (50865)
Comma X-Flow Flush Out Mineral Engine Oil Flush
Millers Oils Diesel Injector Cleaner
Liqui Moly Pro-Line Turbocharger Additive for Initial Fill
Liqui Moly Engine Flush
Liqui Moly Oil Smoke Stop

300ml - SKU 8901

Opie Price
£6.95
Price Beater

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.