Ask Honest John

Most recently answered fuel questions
A friend has suggested that I use the above but would welcome your comments. I drive a BMW 420i cabriolet auto and a Toyota Aygo X auto. I rarely use supermarket petrol and mostly use BP or Jet.
I drive a Skoda Fabia 2021, what type of petrol is best to use?
I have read about a device that plugs into the car under the steering column and claims to reduce fuel consumption by about 35 per cent. Is the claim valid? Is it safe to use? Seems strange that the technology...
Do you have any feedback on fuel savers that plug into a car's tuning system that are being marketed at the moment?
There is an increase at the pumps in France of super ethanol. Which UK purchased cars can use it?
We run a 2012 Fabia TSI Estate with a 103bhp petrol engine and we hang on to our cars until they give up the ghost. Could you please tell men what grade of fuel would be best suited to it in the long term?...
I normally buy from Shell regular unleaded. Is there a difference in quality from companies like Shell and BP compared to supermarket fuel?
I have just found a couple of gallons of diesel oil at the back of my shed. This is probably about 6 or 7 years old. Will it still be OK to use (in my 10 year old Mercedes)?
I have been advised that petrol additives are actually added during fuel station delivery. Non-branded stations, such as supermarkets, receive fewer or or lower capability additives which is partly why...
There are many reports of E10 petrol affecting the performance and economy of cars. I am looking for a new car next year and want to know if the fuel affects highly rated engines or lower rated engines...