Although i have heard that both Amsoil 5W40 euro. and german made Castrol Syntec 0W30 (M0501) are great oils and that they help reduce piston slap noise i would like to have a poll on which you prefer. I have a bad case of piston slap and i would like to know what you all think is better for it and its noise. Also if you think amsoil is better (which is what i have been hearing, then do u think im better with a 5W40 or 10W40)?

im going to run a longer Acdelco filter PF-49 so i need 6 qts right?

I quess im asking which is better for protection and MOST OF ALL noise level on a motor with piston slap

Also. since i have a 2002(OBDII) i have four 02 sensors..i only need to change out the front two. correct? what do the back 2 post cat sensors do?

thanks, im used to my old OBD1 LT1.