Ask Honest John

Most recently answered performance fuels questions
My son has recently bought a Audi R8 and I have told him to use Shell V power. He seems reluctant to use it on the grounds that the fuel consumption is already poor without adding the extra cost of premium...
The handbook for my July 2002 Ford Focus states there is no point in using petrol of a higher octane than 95. Presumably fuel constituents have changed considerably over the last 11 years. So is the handbook...
With all the trouble that is being reported with diesel waxing up this year - what diesel do you recommend?
This is a letter of genuine thanks for continuing to push Shell V Power. I had ignored your advice for what seems like years, but finally gave in on the mention of Nitro (I just loved the film ‘Ronin’)....
I've just bought an Audi S5 Sportback; the preferred petrol is 95 RON as marked on the filler cover. Can I use Shell Vpower or is this too rich?
We recently purchased a low mileage Mazda CX-7 as a second car. The 244HP 2.3-litre turbo engine is very thirsty and the manual calls for 91 octane fuel. Can 87 or 89 octane be used without harm, other...
I have heard a lot of good points about using performance fuel, but I assume it is only really an advantage if using it with a performance car, is this right or would a lot of normal cars benefit from...
I always try to use Shell V-Power super unleaded petrol, but here in Bideford there are no local Shell stations. The next nearest fuel station until recently was Esso, but recently Texaco has taken over...
My grandson is in the motor trade (a qualified technician) and is of the opinion that sole use of top grade fuel, eg Shell V-Power diesel, is damaging to the engine. Is there any truth in this?