Similar thoughts to those above: the oil does no benefit sat on your shelf, keyfob batteries are £1 - my original 2002 battery is still going fine, so it just comes down to whether you believe your engine is full of carbon deposits and if you think they will clean them. A certain brand of petrol claims to do this, or you could just go out and get your engine hot. If it also included 4) A full interior / exterior valet, then it may be worthwhile.
I'd probably spend the £42 on an air conditioning service after 5 years personally.
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TG