I'm currently using NAPA 5w-20 in my 3.3, but have had good results with PYB and Motorcraft, which is my preferred lube.
I would worry not at all about the "Texas heat" requiring a synth - I sincerely doubt the ambient outdoor temps have much effect on the internal operating temps of a motor with a proper cooling system. Only reason to use the synth would be to extend change intervals.
I would worry not at all about the "Texas heat" requiring a synth - I sincerely doubt the ambient outdoor temps have much effect on the internal operating temps of a motor with a proper cooling system. Only reason to use the synth would be to extend change intervals.