which 1 you use?
shopping for oil i have found big differences in price.
for instance: pennzoil ultra platinum synthetic 5 l: $32 cdn;
mobil 1 extended performance synthetic 4.7 l: $64 cdn (am in canada).
why such a large difference? what can you tell? is mobil higher quality so it justifies the double cost?
is there any evidence that proves technically that mobil is so much good?
tests?
thanks