I went to buy some oil today and found Amsoil on sale for $4.85 a qt. I've never tried it because its always been more $$$ than M1,and they seem to be on par as far as quality. This was for their synthetic 10-30 with the gold label. I've never done an UOA,how far should I run it before I send in a sample? My trucks a 2001 with 26K on it.