STP Diesel Fuel Additive Treatment Bundle, Includes Diesel Injector Cleaner and Ultra 5-in-1 Diesel System Cleaner, Cleans Injectors and Restores Performance For A Smoother Engine, Made in the UK

Seems to have improved the performance of my mercedes sprinter. Used with around 50ltrs of fuel & run for approx 2 hours and then another drive the next day. The engine started running very lumpy & was very concerned, spoke to a mechanic and was told this can be normal and run with fresh fuel. All seems good and running without missing firing. Seems to have better power.

I had low expectations about those products. They did the trick in stabilising the erratic idle mode on my astra diesel.

Good priced bundle. Arrived on time - although courier left package on front door step instead of back door as instructed. Not yet used as waiting to reduce fuel in tank before treating. Hoping for improvement in MPG and performance...

Perfect thankyou

This set was a great price and I already highly rated STP products I have found an increase in performance/ acceleration and fuel economy when using this on my older 2011 Jaguar XJ X351 with over 100k miles 3 litre V6 diesel engine.Also this keeps the injectors clear of carboning. It can also assist with DPF cleaning as part of the fuel System cleaner. Again I highly recommend this STP set for anyone with large diesel engines but do a lot of short journeys. ( Note that to successfully clean my DPF I need to do about 1 hour driving (30 miles+ at 3000 revs at least once a month).

I recently tried the STP Diesel Fuel Additive Treatment Bundle, which includes the Diesel Injector Cleaner and Ultra 5-in-1 Diesel System Cleaner. Bought it hoping to give my diesel engine a little refresh—maybe clean out some gunk, boost efficiency, or smooth things out. I followed the instructions: dumped the treatment into a full tank and drove it down to about 1/4 left before refueling again. Performance Observations: Smoother Acceleration: Noticed the biggest improvement here. Throttle response felt a touch more refined, especially when accelerating from lower speeds. No more minor hesitations or rough surges—just steady, smooth power. Low-RPM Improvement: The engine also seemed happier at lower RPMs—less grumbly when idling or cruising in traffic. No miracle transformation, but a subtle uptick in responsiveness. MPG? Nope: Unfortunately, didn’t see any measurable increase in fuel economy (which was my main hope). Maybe over multiple treatments? Or my expectations were too high. Subtle Changes: If you're expecting a night-and-day difference, this isn’t it. The improvements were there but minor—worth it if you’re after maintenance, not a power overhaul. No MPG Boost: A bummer, since cleaner systems should help efficiency. Maybe mileage varies depending on the engine’s condition. Final Verdict: Solid for routine maintenance, especially if your diesel’s feeling a bit sluggish. It delivered on smoothing things out and added a hint of pep, but don’t expect drastic fuel savings. If you’re proactive about injector health, this is a good preventative product—just temper expectations for instant miracles. Rating: 3.5/5 – Does its job, but won’t blow your mind. (Would’ve been 4 with even a tiny MPG bump!) Made in the UK for anyone who cares about origin—no complaints on quality there.

Great fuel additive car runs so much smoother

Bought due to black smoke emissions. So far fuel economy has improved but still have emission issue. However van has run less than 1k miles since adding so will wait and see.