The Best Engine Flush For Diesel & Petrol Engines

By on 22 September 2020 / Leave a comment Updated on: 17th February 2021

Think back to your last oil change. You (or your local mechanic/ dealer) drained the old oil, changed the filter and filled it back up again. Sorry to let you know but you likely didn’t get all the old oil out of your engine, there’s probably dirt and debris left in there and that’s going to stop your new oil doing its job properly.

The oil passageways throughout your engine resemble somewhat of a spider’s web, including plenty of narrow gaps and tight turns. Oil uses these passageways to make its way around the engine, but unfortunately these do get blocked over time. Dirt and debris will, eventually, begin to find their way into these slender corridors and begin to restrict oil flow. Restricted oil flow does not give ideal engine conditions, while a complete blockage could spell disaster.

How Engine Flush Can Benefit your Vehicle

Engine flush is simply added to your engine after draining the old oil, or mixed with it and will make its way throughout those aforementioned passageways and engine internals. As it does so, it will remove these deposits and debris build ups, to give the perfect conditions for your new engine oil. This level of cleaning could not be attained through any other means, try getting into the centre of your engine with a bucket and sponge, that isn’t going to work.

Having a clean engine, means cleaner oil for longer. New oil staying clear of dirt and debris for longer will allow it to perform its job more effectively. An engine using clean oil is a happy one, you could even find increases in performance and fuel economy, while undoubtedly increasing the long-term reliability hugely. Choosing from any of the solutions listed below could save you from serious headaches down the road.

The Best Engine Flush Additives on the Market

Liqui Moly Pro-Line Engine Flush

liqui moly pro line engine flush

Check the latest price on Amazon

Our first recommended engine flush product is from industry leading brand Liqui Moly. Known for their huge line of performance enhancing and reliability increasing products, their engine flush from the pro-line promises huge benefits to your vehicle’s performance and helpful improvements in long term running.

Their engine flush promises to clean the engine from the inside, removing deposits from vital components such as the piston rings and oil passageways. The better lubrication throughout the engine should reduce unwanted noise and excess oil consumption. Clearing the piston rings will also allow the engine to run at the designed compression ratio, giving improved reliability.

One can of their solution is enough to treat an engine requiring up to 5 litres of engine oil, so should be sufficient for most small cars here in the UK. This product is suitable for both petrol and diesel vehicles, including those fitted with catalytic convertors and diesel particulate filters, while also working with all commercially available engine oils.


  • Industry leading brand
  • Thoroughly cleans oil passageways
  • Allows ideal compression ratios
  • Improves lubrication
  • Suitable for nearly all vehicles


  • Most expensive offering listed
  • May require multiple cans for larger engines
  • Requires oil filter to be changed after use

STP Engine Flush

stp engine flush

Check the latest price on Amazon

Those looking for a more economical option need look no further than STP’s engine flush product. Their formula promises to give a deep clean of your engine, matching the product quality that they have become known for within the space. As the company also offers a multitude of performance enhancing fuel and oil additives.

STP’s formula promises to remove the contaminants that are usually left within the engine when performing a regular oil change. The removal of unwanted deposits will help neutralise harmful acids, while also improving lubrication. This enables proper engine function and improved long term reliability as a result. Engine performance and efficiency should also be restored directly after application.

One bottle will treat an engine carrying between 3 and 6 litres of oil, covering most cars currently on UK roads. The product is safe for use in both petrol and diesel engined cars, whilst working with all commercially available oils including mineral and synthetic products. Use at every oil change to maintain maximum effectiveness.


  • Well-known and trusted brand
  • Removes harmful contaminants
  • Neutralises harmful acids within your engine
  • Restores performance and efficiency


  • Requires oil filter to be changed after use
  • Larger engined vehicles may require multiple bottles

Wynn’s Engine Flush

wynns engine flush

Check the latest price on Amazon

Last up is Wynn’s, not to be beaten by their rivals listed above, they are also currently offering a great budget market entry as an alternative to the aforementioned engine flush products. Wynn’s is another brand with an outstanding reputation and is a company that can be trusted after decades in the industry.

This highly concentrated product promises to clean all of the engines oil lubricating systems prior to new oil being added. Their engine flush, Wynn’s states, is able to dissolve varnish, sludge and other common contaminants to prevent corruption of your fresh oil. This will also allow unsticking of internal components and give extra protection for the future.

Suitable for both petrol and diesel applications as well as working with all commercially available engine oils. Simply add the bottle to any engine using between 3 and 6 litres of oil for a full clean, restored performance and improved longevity for your vehicle.


  • Low purchase price
  • Cleans all engine internal oil systems
  • Dissolves unwanted contaminants, allowing new oil to function correctly
  • Suitable for nearly all vehicles
  • Provides additional lubrication for long term reliability


  • Requires oil filter to be changed after use
  • Larger engined vehicles may require multiple cans

In Conclusion

Applying one of the additive solutions above to give your engine that well deserved clean could be the difference in your engine lasting another 10,000 miles or another 100,000 miles. It’s often the issues that you can’t see that will cost you the most should something go horrifically wrong.

Short journeys and infrequent oil changes will make issues more likely, but all engines will develop sludge and carbon deposits that will line oil passageways, like fat build-ups blocks arteries. Don’t let your engine suffer from lubrication issues and get yourself some engine flush. This could be the small spend that makes a massive difference to your car.

If you liked the article, please share, leave a comment below and check out our other exciting articles.

Categorised in:

Jack Gill

Car journalist and fully qualified mechanical engineer, Czok’s newest contributor and long-time automotive writer. Lifetime passion for all things automotive, from new supercars to rusty old hatchbacks. If I’m not behind the wheel, I’m likely under the bonnet or browsing the classifieds. Having spent over 5 years in the automotive industry and under the bonnet of my own car at home, I want to share the knowledge and learning that I have gained, with others without the time to study or the expertise, who just want their car to get them from A to B every day. We aren’t all interested in trawling through endless internet pages and forums. I aim to gather all the information up and roll it into a quick summarised format, to give only the information you really need.

Leave a Reply

Your email address will not be published. Required fields are marked *

Czok Newsletter

Sign up to get breaking news, reviews, opinion, analysis and more, plus the hottest deals!

No spam, we promise. You can unsubscribe at any time and we'll never share your details without your permission.