GC vs Amsoil vs M1

This is for my 02 Mustang GT with 8 k miles. I'm currently using amsoil asl 5w30 with good uoa result but want to switch because of cost.. I have a large stash of M1 5w30's and just today for the first time I bought 20 quarts of GC..first, is GC thicker or thinner than amsoil asl 5w30 at startup and operating temp?? and also how would it compare to M1 5w 30 for my application?? I did a search and hardly found anything about GC and ford 4.6L...BTW the reason I got the GC is for my 91 nissan truck that likes a heavy 30wt oil...thanks for any input..