Pete D basically has it right. Just because an oil claims to be "synthetic" does not rule out that it may be "synthetic" made from petroleum. The term basically means that the original source, whether it be mineral or vegetable has been broken down into chemical groups and then recombined to leave out undesirable portions and include the desirable ones for the purpose intended. Personally I suspect that Mobil One is petroleum based for derivatives. For patch lube Ballistol is my preferred selection and also works well as a barrel protection during storage. All this being said you obviously can experiment all you want and the old belief that petroleum oils will not work with muzzleloaders is not completely true. It seems to be more of a problem with real black powder rather than some of the substitutes.