Michael McAleer answers your queries
From P Logan: I've got a 1998 BMW I bought of a dealer with a full BMW service history. It's now time to service it but the cost to get it done back at the dealer is quite high. It would be much cheaper for me to go to my local mechanic who says he can do the service for about half the price. Will it badly damage the resale if I don't opt for an official BMW service?
It really depends on how long you plan to keep the car. Official services can be quite costly. However, given that the car is seven years old at this stage, the car's value has already depreciated quite significantly. The benefit of having a full official service history is to differentiate your car from similar models when you put it on the market. You have to weigh this advantage against the overall extra cost of getting the official service over the time you plan to keep the car.
Thus, if you're going to run it for three or four more years then your local mechanic may be the most economic choice. However, if you plan to trade it in to a BMW dealer in the next year or so, then it's probably worth the investment. A word of advice: shop around for servicing prices. There is a significant difference in price even between official dealers and it may be worth travelling a few miles.
From James Murphy: Could you please advise where I could buy a conversion table for mpg to litres per kilometre. I can do the conversion mathematically, but it is a nuisance.
You are not the first person to ask for this, so it's probably about time we addressed the matter. There are no easy conversion tables on offer at present on the internet, but here's a quick guide to some common rounded figures:
10 mpg = 28.2 l/100km
15 mpg = 18.8 l/100km
20 mpg = 14.1 l/100km
25 mpg = 11.3 l/100km
30 mpg = 9.4 l/100km
35 mpg = 8 l/100km
40 mpg = 7 l/100km
45 mpg = 6.3 l/100km
50 mpg = 5.7 l/100km
From P Cullinane:I'm sure you've had this query before, but how do you remove oil from a driveway? My old Toyota sprung a leak and though I've got it fixed, there's a terrible stain on our new driveway. My wife is less than impressed. How can I redeem myself in her eyes?
I know how you feel. At one stage, our driveway had so many oil stains, I seriously considered covering the whole thing in oil to get some sort of consistency throughout.
I've tried various methods, without much success.
There is one way that has been recommended to me. First spray the area with paint thinner in a spray bottle. Then cover it in sawdust or some other absorbent material.
There are also several products available at motor factors stores for just such tasks, but I can't vouch for any of them as being the perfect solution.
The key, it seems, is to treat the stain as soon as possible: the older the stain, the more difficult it will be to remove.
From S Mooney: Further to last week's query about overcharging for petrol, why is it that so many stations can get away with charging such ridiculous prices for fuel? Also, is there any basis for buying so-called 'performance' fuels on sale at some petrol stations?
I'm not entirely convinced that these 'performance' petrols do anything other than keep your engine clean. That in itself is a worthy aim, but it would seem to a cynic like myself that at the root of these products is merely a desire by the oil giants to differentiate their fuel from all the rest, and thereby cushion themselves from whatever competition there is in the marketplace.
Just because you use a 'performance' fuel, you're not suddenly going to turn your Nissan Micra into a Ferrari Enzo overnight, or even over the lifetime of the car.
What most of these companies actually claim is that their premium fuels help to prevent the build-up of dirt and deposits on the valves, and in that way keep the engine at optimal performance. Why they can't simply make all fuels as clean as this is another matter, but to me it always comes across as more of a marketing exercise than a chemistry-based one. Most of them also require you to use them over an extended period, and you must keep using them to maintain the same level of efficiency. Of more importance is to try and avoid the dirty fuel that's on sale in some places.
As for price, the best way to get a good deal on fuel is to shop around. The fact that some forecourts can charge €1 per litre while neighbouring stations charge €1.08 and still have customers seems to reflect more on the idiocy of some motorists as much as the profiteering of some petrol retailers. We beseech all readers: shop around.
Send your queries to: Motors Help Desk, The Irish Times, Fleet Street, Dublin 2 - or e-mail them to motorshelp@irish-times.ie