I did some research on a thread of this same question a few years back.
What I came up with is to use any major brand( and usually on sale) of synthetic but a viscosity of 0w-20w. The formulas of todays oils break conventional thinking. A 0w allows the oil to circulate faster upon start up when most wear occurs and the 20w is what is spec'd for these motors when warm or hot. Do some research your self. :smt102You may be surprised at what you find:smt023There was another member here who also used 0w-20w. I believe he was an Amsoil distr.:rockon_ford