Fuchs are very good oils,up ther with the best. Some oil manufactures with do crazy deals for bulk orders,so they will probably have only the 1 oil grade and use it in anything, I don't know? It's more critical in some cars than others 10w-40 was considered fine for 400h 05-06 but not a year round or not recommend for temps below -10 so the 5w-30 became the norm 06 onwards .
Basically their going to do an oil and filter changed for £40 quid,just doesn't add up but what they might do is produce a list as long as your arm of things you need doing, sir your shockers are leaking (after they have sprayed duck oil on them) your brakes are binding( but rather the strip and clean them,will try and sell u discs and pads all round then telling you, oh it's your calipers too) and your tacking out (it might be but to what degree) I know it goes on its happened to friends of the family, but the usually pick on the vulnerable some people panic oh can't do with out my car and in a lot cases with have it done and that's how they make ther money.
I wouldn't compromise my engine for the sake of a few quid, engine rebuilds are expensive. Interesting to see nelmo used a cheap own oil in his bike and it went on to do96,000 miles fore he sold it, in my bikes( yamaha r1/fz1) I use the oil q8 10w-50 racing and change it every 3000 miles without fail.(be interested in finding out what year and size bike nelmo had?).
Another question I would ask is why a expensive quality car then compromise on it's maintaineance.
Let me know what service is req'd, mileage and number of book stamps and I'll tell you what's req'd on the particular service.
Cheers Shaun