Oil-Wynn’s Diesel Injector Cleaner Review: Cheap Insurance or Money Down the Drain?
At £6-10 per bottle, Wynn’s Diesel Injector Cleaner is one of the cheapest maintenance products you can buy. Pour it in, fill up, and drive. But does squirting a few hundred millilitres of detergent into 50 litres of diesel actually do anything measurable to your injectors?
What It Does (and Doesn’t)
First, let’s clear up a common confusion. Wynn’s makes two diesel fuel additives with similar branding:
- Wynn’s DPF Cleaner = cerium catalyst that helps burn off soot in the particulate filter
- Wynn’s Diesel Injector Cleaner = detergent package that dissolves carbon deposits on injector nozzles
They target completely different problems. The injector cleaner won’t help your DPF, and the DPF cleaner won’t help your injectors. You can use both if needed, but they’re not interchangeable.
The Injector Cleaner contains a detergent/dispersant package (likely polyisobutylamine-based, though Wynn’s doesn’t disclose the exact chemistry) along with corrosion inhibitors and lubricity improvers. When mixed with diesel, the detergent molecules attach to carbon deposits on the injector nozzle tips and gradually dissolve them over a tankful of driving.
Does Anyone Actually Notice a Difference?
This is where honest reviews get tricky, because the results are subtle on a well-maintained car.
On neglected diesels with 80,000+ miles and irregular servicing: Users on forums like HonestJohn and PistonHeads report noticeably smoother running, reduced black smoke on acceleration, and marginally better fuel economy (1-2 mpg improvement). These are engines where injector nozzle deposits have had years to build up, and the cleaning effect is most pronounced.
On well-maintained diesels with regular servicing: Most owners honestly say they can’t tell a difference. The typical response is: “Can’t say I noticed anything, but I use it every 5,000 miles as cheap insurance.”
And that second response is actually the right approach. Injector cleaning is most effective as preventative maintenance — keeping clean injectors clean — rather than as a rescue product for badly fouled injectors. A seriously coked injector with a disrupted spray pattern needs professional ultrasonic cleaning or replacement, not a £7 fuel additive.
The Honest Truth About Fuel Additives
Here’s something the marketing won’t tell you: UK diesel fuel already contains detergent additives. All fuel sold in the UK must meet BS EN 590 standards, which include basic deposit control. Premium diesels (Shell V-Power, BP Ultimate) contain significantly higher detergent concentrations.
So does Wynn’s add anything beyond what’s already in your fuel? Probably yes, but the margin of improvement depends on what fuel you normally use. If you exclusively run Shell V-Power, the incremental benefit of Wynn’s is minimal. If you fill up at the cheapest supermarket pump, the benefit is more meaningful.
Price and Availability
- Price: £6-10 for 325ml (one tankful)
- Where: Halfords, Euro Car Parts, Amazon UK, most petrol station shops
- Usage: One bottle per tank, every 3,000-5,000 miles for maintenance
Our Verdict
Worth buying? Yes, at £7 it’s genuinely cheap insurance. It won’t transform your engine, but it’ll help keep injectors clean between services. Particularly worthwhile if you use supermarket diesel.
Don’t expect: miracles on badly fouled injectors, dramatic fuel economy improvements, or a substitute for professional injector cleaning.
Best used as: regular preventative maintenance every 3-5,000 miles, combined with the correct low-SAPS engine oil and at least one weekly motorway run for your DPF.
Rating: 3.5/5 — Does what it says, but the results are subtle on well-maintained engines. The low price makes it easy to justify regardless.
Sources: Wynn’s product technical data, HonestJohn.co.uk diesel maintenance forum threads, PistonHeads diesel owner experiences, BS EN 590 UK fuel specification.