Ask Honest John

Most recently answered diesel particulate filter questions
Last week you wrote about DPF clogging to contaminate lubricating oil. My computer says I have a reduced oil level but the dip stick confirms correct amount. I get black smoke on accelerating.
Recently retired and want to buy a used car that has a very comfortable ride. I have considered a Jaguar XF or Lexus IS250 but would welcome your opinion and/or further recommendations. Budget £25-28K,...
Finally I have made my mind up to go for a used Mondeo estate, about 1 year old. I have discovered about possible problems with the DPF, as I would only be doing approx 3,000 to 4,000 miles per year, mostly...
My Hyundai Santa Fe diesel auto has 62k miles, is 4 years old and hence still has one year warranty. The car has been and still is ideal for my needs and I have no particular wish to change it. However...
Can an adblue tank fitted to a diesel powered car at all?
I am retiring in January next year, my current company (lease) car (Skoda Octavia L&K Estate 20. DSG) expires when 4 years old in December. Mileage at that point will be around 32,000. I am considering...
Considering Mercedes CLC '08/'10 180 Kompressor petrol auto. Daily drive is five miles, weekly some 30 mile trips, monthly an occasional 60+ miles. Should I go for a diesel auto though? Don't like...
Do you know of any forthcoming changes to VAG diesels, such as chain cam and/or less problematic DPF? Are DMFs used on automatics/DSGs by VAG or Hyundai? Will VAG be introducing the more efficient 7-speed...
Please explain why Mazda 6 2.2L diesels do not have the same DPF problems as the Mazda 6 2.0L diesel (where the sump can fill up with diesel oil)?
I have a Skoda Yeti 2.0 Diesel with DSG. 5,000 miles a year, 40% of my journeys less than 5miles. Would a fuel additive reduce the chance of clogging and, if so, how often should I use it?