Are dealer-only oils any different from those publicly available?

I just received my car back from its first dealer service and saw I had been charged £60 for 3 litres of Castrol magnatec 5w30 c2 oil. I showed how I could but the same grade myself for less than half of that price, to be told that the garage uses 'professional' grade oil, unavailable to a rube like me. Is there any difference in performance between professional grade and consumer grade? If so, is it really worth 100% premium?
The dealer service manager was lifting your leg. Just as a restaurant marks up wine by between 50% and 250% compared to supermarket or wine merchant prices, garages do the same.
Answered by Honest John on

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