In looking at another thread: http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=010671 where a poster asked if his engine would be hard on oil, I got to thinking about my cars. '94 Merc Sable 3.0L - 6cyl - 4.5 qts '87 Bonniville 3.8L - 6cyl - 4.0 qts '02 Accent 1.6L - 4cyl - 3.5 qts I always thought my Accent should hold more oil than it does, but looking at the above cars there is more oil/cylinder or per Litre than the two v6's. However, the 4-cyl runs a lot faster, about 3000rpm at 65 as opposed to the 6cyl's at a little over 2000 rpm at 65. I would think that the higher operating speed of the 4cyl would be harder on the oil and would require a larger capacity/litre than a 6cyl. Is this why as in the other post, I believe a Nissan 3.0L - 6cyl holds only 3.5quarts? Expected lower overall operating speed? That is a truck engine also, it just doesn't seem right.