All personal preference i spose... whenever we get a customer in the shop that specifically asks for synthetic oil (believe it or not SOME people know the difference to ask lol) we always order a 6 case of Mobil 1. I spose that'* just because it'* what our supplier carries but it seems like good fluid. I know this wasn't in the original discussion, but what about Royal Purple? Isn't that stuff supposed to be great? Personally on high mileage motors, i run 4 quarts of 10W30/40 depending on season and a quart of Lucas oil treatment.
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