For a car in storage, with only monthly starts, is it best to use synthetic or mineral oil? Will the synthetic stand up better to contaminants and fuel dilution, or is the use of synthetic just a waste of a good oil?
My options are:
Amsoil 5w-30 (ASL synthetic)
Castrol 0w-30 (German synthetic)
Penzoil 5w-30 (Purebase mineral)
Esso XD-3 15w-40 (HDEO mineral)
Thanks