Try explaining that to someone who has never changed their own oil and complains that their bill is $13 more the the previous persons. I always tell them that if it was my choice it would be a $30 differance. And you should see the confusion on rednecks faces when I tell them that their new Ford truck takes 5w20. Their responce is always the same "I don't want to put no piss watter 5w20 in there, put 10w40 in." Then I tell them Ford will void their warrenty if the run anything but 5w20 in it. Sure pisses them off.