With 5000 miles on the clock, my Land Rover Discovery Sport 150PS calculates that diesel dilution caused by active regeneration of the DPF is currently 4.2 per cent by volume, against a maximum of 7.0 per cent. JLR have reset the service interval indicator under warranty from 8350 additional miles to 19850 additional miles and told me in writing that I should stick to the standard intervals, i.e. the first oil service to be done at 21,000 miles total, or two years if earlier. In the meantime, they say I should ignore the service interval mileage indicator and only take it for an oil change if the car requests one due to the diesel contamination rising towards maximum. This is all well and good but the quote from a local dealer for an oil service was £528.66 and they refused to discuss a price for an abbreviated service involving just the oil and filter. I feel they are treading a fine line in terms of anti-competitive practice. I'll deal with that in due course but at present I'm about to send an oil sample to a laboratory for a report on the actual percentage of diesel present. Under vertical block exemption (VBER), I believe that I can have the oil changed on a new vehicle at any garage, provided that they adhere to the manufacturer's specifications for parts and this will not invalidate the manufacturer's three year warranty. Can you please confirm that I have understood this correctly?