Best STP Engine Oil Additives of 2026

Name: STP Engine Flush for Petrol & Diesel
Brand: STP

Joseph Prokop

Last Updated: 11 Feb 2025

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Engine Oil Additives from STP are designed to improve the performance and lifespan of your vehicle's engine. These additives work by enhancing the properties of your engine oil, providing better protection against wear and tear, reducing friction, and improving fuel efficiency. STP offers a range of additives, including those that help to clean and protect your engine, reduce engine noise, and stabilise oil pressure. With over 60 years of experience in the automotive industry, STP is a trusted brand that offers products to keep your engine running smoothly.

At a Glance: Our Top Picks

#TOP 1

STP Engine Flush for Petrol & Diesel

9.8

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#TOP 2

STP Smoke Treatment for Petrol Engines 450 ml

9.7

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#TOP 3

STP Engine Stop Leak and Degreaser Set

9.5

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Top 9 STP Engine Oil Additives

#TOP 1

STP Engine Flush for Petrol & Diesel

STP
GST62450EN06
450ML

STP GST62450EN06 Engine Flush for Petrol & Diesel Engines 450 ml

The STP Engine Flush is designed to keep your engine in top condition. It effectively removes harmful sludge and deposits, ensuring that your engine runs smoothly. While flushing, it protects the engine, preventing any potential damage. This product also helps to stop and prevent minor oil leaks, which can save you costly repairs. Additionally, it neutralises harmful acids, promoting a healthier engine environment. Using the STP Engine Flush can enhance the longevity and performance of your vehicle.

9.8

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What We Like

Removes harmful sludge
Protects engine during flushing
Stops minor oil leaks
Neutralises harmful acids
Proudly made in the UK

#TOP 2

STP Smoke Treatment for Petrol Engines 450 ml

STP
GST64450EN
500ML

STP Smoke Treatment for Petrol Engines 450 ml

The STP Smoke Treatment is designed to enhance your petrol engine's performance and longevity. It effectively reduces engine wear, ensuring that your engine remains in excellent condition. Additionally, it provides extra protection, giving you peace of mind during driving. By reducing deposits, it keeps vital engine parts cleaner, which can enhance efficiency and overall performance. Furthermore, it fights oil oxidation and breakdown at high temperatures, helping to maintain optimal engine function even under demanding conditions.

9.7

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What We Like

Reduces engine wear
Extra engine protection
Reduces engine deposits
Fights oil oxidation

#TOP 3

STP Engine Stop Leak and Degreaser Set

STP GST63300EN Engine Stop Leak for Petrol & Diesel Engines 300 ml & GST73500ENP Engine Degreaser Professional Series 500 ml

The STP Engine Solutions set includes two essential products for your vehicle. The Engine Stop Leak helps to stop minor oil leaks and conditions engine seals, ensuring a smoother operation. It is compatible with both regular and synthetic motor oils, giving you flexibility in your choice. Additionally, it contains no solids that could clog filters or inhibit oil flow, providing peace of mind. This means you can maintain your engine's performance without worrying about potential blockages.

9.5

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What We Like

Stops minor oil leaks
Conditions engine seals
Compatible with all motor oils
No clogging solids

#TOP 4

STP Engine Flush 450ml for All Engines

STP
ef108

STP Engine Flush 450ml For Petrol Or Diesel Engines

The STP Engine Flush is a 450ml product designed for both petrol and diesel engines. You can use it with every oil change, ensuring your engine stays clean and performs at its best. It is compatible with single multi-grade mineral or synthetic oils, providing versatility for various vehicles. By using this engine flush, you help remove harmful deposits that can build up over time, leading to improved engine efficiency and longevity.

9.4

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What We Like

Compatible with all engine types
Easy to use with oil changes
Removes harmful engine deposits
Works with various oil types

#TOP 5

STP Oil Treatment for Diesel Engines 600ml

STP
61300EN-2

STP® 61300EN Oil Treatment for Diesel Engines 300ml - 2x300ml = 600ml

The STP Diesel Oil Treatment is specially formulated for all diesel engines, ensuring optimal performance. It contains essential additives that are typically found in premium diesel engine oils, which means you can maintain a high level of engine care. When you use this treatment between oil changes, it effectively replaces burnt-out minerals and additives in your engine oil. This not only helps in keeping your engine running smoothly but can also significantly reduce your diesel operating costs over time.

9.4

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What We Like

Specifically designed for diesel engines
Replaces burnt-out additives
Reduces operating costs
Easy to use

#TOP 6

STP 300 ml Engine Oil Treatment

STP
5018704350074
Other

STP Oil treatment - 300 ml

The STP Oil Treatment is a reliable product designed to enhance your engine's performance. Its good quality ensures that your engine operates smoothly, providing you with peace of mind. You will find it easy to use, making it suitable for both novice and experienced users. Moreover, this product offers excellent value for money, allowing you to maintain your engine without breaking the bank. With STP Oil Treatment, you can trust that your engine will run efficiently and effectively.

9.4

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What We Like

Good quality product
Easy to use
Value for money

#TOP 7

STP 300 ml Diesel Oil Treatment

STP
5018704352078
Other

STP Diesel oil treatment - 300 ml

The STP Diesel Treatment is a premium quality engine oil additive designed for ease of use. It helps enhance your vehicle's performance, ensuring a smoother drive. By using this product, you can improve fuel efficiency, which can save you money over time. It's also effective in reducing engine wear, promoting longevity for your vehicle. With its straightforward application, you'll find that maintaining your engine's health has never been simpler.

9.2

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What We Like

Premium quality formulation
Easy to apply
Enhances engine performance
Improves fuel efficiency
Reduces engine wear

#TOP 8

STP Engine Stop Leak for Petrol and Diesel

STP
63300EN

STP® 63300EN Engine Stop Leak 300ml

STP Engine Stop Leak is designed to address minor oil leaks in both petrol and diesel engines. Its unique formulation contains a special agent that helps renew polymer seals and gaskets, which can become damaged over time due to heat. This product is compatible with all motor oils and will not clog filters or affect engine components. By rejuvenating dried-out seals, it provides extra protection against leaks, ensuring smoother engine operation and potentially saving you from costly repairs.

9.0

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What We Like

Stops minor oil leaks
Compatible with all motor oils
Rejuvenates seals and gaskets
No clogging of filters
Safe for engine components

#TOP 9

STP Heavy Duty Engine Degreaser 500ml Pack

STP
STP-73500EN-3

STP Heavy Duty Engine Degreaser 500ml 3pk

The STP Engine Degreaser is an ideal solution for keeping your vehicle’s engine clean and efficient. It is suitable for a wide range of engines, including those in cars, lorries, vans, and tractors. This powerful degreaser penetrates deep to dissolve heavy dirt and stubborn deposits, ensuring a thorough clean. By using this product, you can maintain optimal engine performance and prolong the lifespan of your vehicle, making it a valuable addition to your maintenance routine.

9.0

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What We Like

Effective for various engines
Dissolves heavy dirt easily
Enhances engine performance
Convenient packaging

Editor's Notes

During our STP engine oil additive research, we found 9 STP engine oil additive products and shortlisted 9 quality products. We collected and analyzed 23,058 customer reviews through our big data system to write the STP engine oil additives list. We found that most customers choose STP engine oil additives with an average price of £13.64.

The STP engine oil additives are available for purchase. The top 9 picks range in price from a low of £5.00 to a high of £32.00, find the one that fits your budget.

Written by

Joseph Prokop

Joseph is a seasoned writer who's also passionate about automotive. His passion for automotive care and maintenance fuels his drive for more knowledge in the field. He currently resides in Middlesbrough, where he finds time to write informative contents on automotive. His automotive related articles are quite popular in journals around the world. Joseph continues to use his wealth of experience in the industry to create helpful guides on automotive.