I've used Pennzoil forever. Both of my 1989 Chevy trucks used about a quart between oil changes, but they both have 175K miles on them. Someone told me that Pennzoil will tend to used more oil than other popular brands, such as Valvoline or Quaker State. So far, my 1999 Chevy truck hasn't used any oil and I've put almost 1500 miles on it, but I don't know what brand is in it. I'm getting ready to change it this weekend. What brands do you use and why?