Marcus RodriguezDiesel fuel additives4 products
If you want a reliable, all-rounder for maintenance, go with STP Ultra 5 in 1. For those dealing with specific emissions or DPF issues, Cataclean is the heavy lifter, while the Wynn's options are solid for pure performance and combustion efficiency.
Routine maintenance
Budget-conscious cleaning
Emissions issues
Performance restoration
| Feature | STP Ultra 5 in 1 | Wynn's Extreme | Cataclean Diesel | Wynn's Formula Gold |
|---|---|---|---|---|
| Price | £11.49 | £7.49 | £16.73 | £14.99 |
| Bottle SizeCataclean and Wynn's Formula Gold provide the most volume per treatment. | 400 ml | 325 ml | 500 ml (winner) | 500 ml |
| Primary FunctionCataclean covers a broader range of exhaust components than the basic cleaners. | 5-in-1 cleaning | Extreme deep cleaning | 8-in-1 fuel/exhaust system (winner) | High performance treatment |
Routine maintenance
A solid, dependable cleaner for keeping your fuel lines and injectors free of gunk. It is a no-nonsense additive for the everyday driver.
Budget-conscious cleaning
This is a compact, punchy treatment that helps quiet down a noisy engine. It gets the job done without breaking the bank.
Emissions issues
The big gun for when your DPF or catalytic converter needs a helping hand. It is the gold standard for passing those tricky MOT emissions tests.
Performance restoration
Focuses heavily on combustion efficiency, making it great for sluggish, high-mileage engines. It turns that black smoke into a cleaner exhaust.
Listen, I have seen enough gummed-up injectors to know that not all fuel additives are created equal. You have got the STP Ultra 5 in 1 and the Wynn's Extreme acting like daily vitamins for your engine, keeping the carbon at bay and the idle steady. They are easy to toss in when you fill up, and they do exactly what they say on the tin.
Then you have the big hitters like Cataclean and the Wynn's Formula Gold. These are for when things are starting to feel a bit choked up. Cataclean is the one I reach for if the DPF light is looking at me funny, while the Wynn's Formula Gold is more about getting that lost power back under your right foot.
If your engine is running smooth, stick with the cheaper maintenance bottles. But if you are chasing an MOT pass or your turbo is feeling sluggish, the extra quid for the heavy-duty stuff is money well spent. Just remember, no bottle of liquid is going to fix a busted mechanical component, so don't expect miracles if your parts are already failing.
If you are just looking to keep your diesel running clean for another ten years, the STP Ultra 5 in 1 is your best bet for regular maintenance. For those facing MOT emission worries, Cataclean is the one to grab.
If your engine feels like it has lost its spark and is blowing smoke, the Wynn's Formula Gold is the tool for that job.
Prices on amazon.co.uk as of October 12, 2026. Prices may change.
Disclosure: We share affiliate links and can earn some money when you click on any of those.