# STP Petrol Fuel System Cleaner 400ml

STP Petrol Fuel System Cleaner is a concentrated 400ml treatment for petrol engines. The listing says to add it to the fuel tank every 4,000 miles and claims it dissolves deposits throughout the fuel system. Customer feedback reports smoother running and performance improvements, though fuel-economy experiences vary.

- [Original product page](https://bargainpostbox.co.uk/product/stp-petrol-fuel-system-cleaner-400ml)
- [View offer](https://bargainpostbox.co.uk/visit/stp-petrol-fuel-system-cleaner-400ml)
- Market: UK
- Language: en-GB
- Currency: GBP
- Brand: STP
- Model: ST50400EN
- Category: Cars & Motorcycles > Auto Parts & Maintenance > Vehicle Oils & Fluids
- Price: 6.80 GBP
- Previous price: 8.00 GBP
- Discount: 15%
- Price checked: 2026-11-12T14:41:12.498Z
- Rating: 4.5 / 5
- Reviews: 810

Prices and deal status are the latest recorded data, not a guarantee of availability. Confirm the price and availability with the store.

## At a glance

- A single treatment is claimed to dissolve deposits from the entire fuel system.
- The listing says the cleaner is suitable for classic and modern petrol engines, including engines with catalytic converters.
- Manufacturer claims include support for smoother starts and reduced exhaust emissions and fuel consumption. These are claims, not guaranteed results.

## Pros

- The 400ml concentrated petrol treatment is intended for use as a routine fuel-system maintenance additive.
- Customer feedback reports improved performance, smoother running and effective cleaning, which may appeal to drivers seeking general maintenance rather than a repair product.

## Specifications

### Identity
- Brand: STP
- Model: ST50400EN
### Dimensions and weight
- Dimensions listed: 35.35 x 16.73 x 7.13 cm; 400 g
- Weight listed: 400 g
### Product details
- Container volume: 400ml
- Special feature: Concentrated
### Recommended use
- Application interval: Simply add to your fuel tank every 4000 miles
- Engine compatibility: Suitable for both classic and modern engines, and for catalytic converters

## Before you buy

- The listed benefits for performance, emissions, fuel consumption and hard starts are manufacturer claims and are not guaranteed outcomes. Follow the product label and vehicle guidance when using fuel additives.

## A good fit for

- Petrol-car owners looking for a fuel-system cleaner to add during routine maintenance.
- Owners of classic or modern petrol engines, including vehicles with catalytic converters, as stated in the listing.

## Less suited to

- Diesel vehicle owners, as this product is listed for petrol engines.
- Drivers expecting a guaranteed improvement in fuel economy or a substitute for diagnosing mechanical faults.

## Customer feedback

Customer feedback commonly highlights improved engine performance, smoother running, quality and fuel-system cleaning. These reports may matter to buyers using the treatment as routine petrol-system maintenance, but they do not establish a guaranteed result. Experiences with fuel economy are mixed, so the claimed consumption benefit should not be assumed.
- Positive themes: Customers report better engine performance and smoother running.
- Positive themes: Feedback also speaks positively about product quality and fuel-system cleaning.
- Mixed feedback: Fuel-efficiency feedback is mixed. Some customers report better economy while others notice no improvement.

## Frequently asked questions

### How often does the listing recommend using this cleaner?
It says to add it to the fuel tank every 4,000 miles. Check the product label and vehicle guidance for application instructions.
### Which engines is it listed for?
The listing says it is suitable for classic and modern petrol engines and for catalytic converters.
### Will it improve fuel economy?
The manufacturer claims the cleaner helps lower fuel consumption, but that result is not guaranteed. Customer feedback on fuel efficiency is mixed, with some reporting improvement and others noticing none.

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## Add-ons

- [Redex Petrol System Cleaner 250ml, Petrol Injector Cleaner To Remove Harmful Deposits, Maximise Performance & Increase Fuel Economy Fuel Additives For Petrol Engines, Suitable For Hybrids](https://bargainpostbox.co.uk/visit/stp-petrol-fuel-system-cleaner-400ml)
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## Images

![STP Petrol Fuel System Cleaner 400ml — 1](https://bargainpostbox.co.uk/i/p6HM8LH1cSo8bjHuyXX3D4TwggS4n7RBugfPOZH02TMUolkecGf7jkcD8RhjgV7APqSfZjoD9OokeQ3JH_txyXTp-HGT-vjBhgzajjYUczjpNbSdQWUPSfHm.jpg)

![STP Petrol Fuel System Cleaner 400ml — 2](https://bargainpostbox.co.uk/i/ifK01-ZHDGSYiOmZ701jxdpHt2Ou0uxLC6JTOYmmSpnkHnrCohIZEIsL5mcqxRRm0qOqh7vtVHRdBuUxnl1XLmfldr_-AbZVDxzL_p_qEtsWkBR8iLyU5vPR.jpg)

![STP Petrol Fuel System Cleaner 400ml — 3](https://bargainpostbox.co.uk/i/KxJmJXQaDrnvrIzNs0kgxsha2VTdJM6x1pCE9gTkAemyMzryijdx0sXOPkEzT0H_OTZhd8VxR9SpjdbyoadssuDVNwONuu3VeqIxqSxbGx1ZjsldBlneZjy4.jpg)

![STP Petrol Fuel System Cleaner 400ml — 4](https://bargainpostbox.co.uk/i/ZfInInHQVlo4sVHWRWToAVnzUHIB5VclC_Fqnozp83FXH2JNzMrvLWVCtsZZj1LiN0MtCI1cvFUPeZweAZ62UvmZhf3wkMhw41Gx1WGotb8eILgvEHzsuiI9.jpg)

![STP Petrol Fuel System Cleaner 400ml — 5](https://bargainpostbox.co.uk/i/7QwL9uowMJT5rh8-4906zUXfLNZ0gOEamp4t5MYB7DB_hDmVPj90xzKmHzg96lnLbZndUFCsz5bopunBH7cXGJzL6M4NVe4wn0py6S2gopKqhKY66YvdwhfA.jpg)

![STP Petrol Fuel System Cleaner 400ml — 6](https://bargainpostbox.co.uk/i/W6cJDP_Lc9_Utc7-WQ6RSKJwCwMnR_Fn1tfjOs_0kdlsqIKa97xmYtMgmv_EA9V7OgZfP3oCNRkXwHJ1MhaMJVaxtRZWL0Tb3X1LEU6tz-BXR9vzsqoLO9zK.jpg)