Wow, this is one of those questions that gets us all fighting.
If it where my engine I would run Royal Purple 10-30 in the winter and 10-40 in the summer. If you are adverse to synthetics then I would use Valvoline all-climate in the same weights. But that is just me, I'm sure you will get 400 differing suggestions and some serious stone throwing.
I have had exceptionally good results with both brands and some very bad experience from other brands.