Ask Honest John

Most recently answered additives questions
What fuel should I use in my 1963 Velocette?
I have just acquired a K reg Volvo 850 GLT with just 25,000 fully-documented miles on the clock. Is it okay to use super-unleaded fuel in this car? Also, would it be wise to use a petrol additive such...
Should I add injector cleaning fluid to my 2007 BMW 525d diesel engine?
My Mazda3 1.6 diesel is due for its second annual service shortly and has done 7300 miles. The garage says that Mazda recommends a bacterial cleanse of the ventilation system for £24.95 and a brake fluid...
I was interested to read your recent comments about certain vehicle models appearing to be DPF trouble-free. Is this because they have markedly different systems for regeneration of the filter, or some...
I notice you were yet to be made aware of any DPF issues with Mazda Skyactiv diesels so I thought you might like see the attached which comes from the May 2013 issue of Diesel Car. Are you seeing any evidence...
Our 2002 Renault Scenic 1.6 automatic has clocked exactly 45,000 miles. On a recent motorway journey of 150 miles I decided to check the economy and was horrified to find it was only 26mpg. We only use...
Why will no one do an in-depth review on supermarket v/s the big four fuel suppliers? I am a tanker driver (not fuel) and over the years have asked at least six fuel tanker drivers if there is a difference...
I have a problem with my 2011 Ford Focus 1.6TDCI (old model). When first purchased it gave me 54mpg. 14 months later it has now reduced to 47mpg with the same sort of driving pattern. I have tried to add...
We are focusing on news regarding fuel additives for use in diesel engines. With diesel cars now over 50 per cent market share in the UK, and very significant numbers in use, there's a valid story concerning...