Garages are in general struggling to survive and one area where they can generate some big money is in the
they supply and what they charge for it. Always question what is going into your car even if you are paying a premium price for it as even the poorest oils can generally pass the low specifications of most manufactures.
I would suggest that the reason that a 10w-40 went into your car is that this can be sourced cheaply and thatís unfortunately what you will have; A 5w-30 would be a better
as the refining methods would have to be better to get it to that specification, now a 0w-30 would start to move you into a quality area!
I stand to be corrected but Elf
doesn't really exist and are owned and have oils supplied from elsewhere, good luck.
Decent oils are made by the likes of Mobile, Motul and the top in testing Amsoil, but hey its your money and your car. If you don't want to spend an extra few quid a litre to protect your substantial investment, get longer service intervals and better protection (which actually saves you money) never mind a couple more miles to the gallon I'm sure the car manufactures will be please to see you back in the showroom in a couple of years.