You didn't mention what engine you are running. There is no TCW3 oil on the market today that is going to ruin your engine, assuming it was designed for TCW3 and at the ratio you are using it. With that said, each have different additives and different goals in mind with different price points.
Walmart oil --- well i've never tried that stuff and dont plan to, from my understanding its the same as regular pennzoil. I do not support wallyworld in anyway shape or form.Many guys have ran it and they seem to like it.
Pennzoil Syn blends -- Very clean burning and low on smoke. $17/gallon puts it only $3 more than walmart stuff. This is what I run and if probably the most popular non-OEM oil ran by most.
Yammy oil -- Never ran it myself, but it is full of Moly which results in soot/carbon build up.High level of protection -- However Decarb and/or anti carbon additives are needed more often.
Merc/quicksilver Syn blend-- Also a Good oil, but with tons of Moly in it. Decarb and/or anti carbon additives are needed more often.
West marine/Cabellas syn blend -- Same as the Pennzoil with a rebranded label. Cost more than I can get the pennz for.
On the left is Pennz syn blend, the right is quicksilver premimum plus (syn blend)
[FONT="]Additives(PPM):[/FONT]
[FONT="]Molybdenum -2/1050[/FONT]
[FONT="]Phosphorus - 9/32[/FONT]
[FONT="]Zinc - 15/39[/FONT]
[FONT="]Magnesium - 0/0[/FONT]
[FONT="]Calcium - 38/120[/FONT]