Petrol " if you go to the refinery, you"l see all the trucks, [ with Asda, tesco, brogan, etc,] filling from same bulk tanks, As for oils, you hardley ever see mineral oil nowadays , its near all synthetic or semi-synthetic, either way,,,its 10 times better than oils in 1970s , 25-1 it was common then, nowadays 50-1 is commonplace , tells you summat,,,,