synthetic oils

Better to re post for new questions. RE: Wal-Mart brand oil, someone said earlier Mobil 1 is the best synthetic, so that answered - sort of. There are other brands that are good, like Red Line and Royal Purple, but Mobil 1 also has the PAO base stock and is widely available. There are various opinions about oil. If it meets the minimum API standards, you should be fine. The confustion in synthetics arose when Valvoline won a court case allowing them to call their "hydrocracked" base oil "synthetic" because it had been altered, although not "fully synthetic base stock." The additive packages are almost certainly different with the Wal-Mart brand, also. High mileage oils can swell the seals - I personally don't like that idea, because once you've done that, don't believe you can ever go back to conventional oil. Auto-rx cleans the seals along with other internal engine areas, supposedly restoring seal flexibility, versus artificially swelling them. As far as your engine having wear, one good indication would be how much oil does it use - generally indicitive of piston ring wear. Especially with Toyota, higer mileage doesn't necessarily equate to more engine wear. Another key factor, is how you drive the car when cold. More wear occurs then.