I will start off by saying I am the owner of a Dodge Cummins that I am currently running Petro Canada Duron Synthetic 5w40 in, but I recently purchased a 1992 Pontiac Bonneville as a second vehicle. It will primarily be used as my "grocery getter" particularly in the winter months. I would like the car to last me for quite some time so I am trying to decide which oil would be my best option for the car. As I mentioned the car will primarily be driven on short trips averaging 2-6 miles. It will also be used as an my primary vehicle to respond to emergency calls. This means getting in the car in the middle of the night when the temps are in the single digits and driving it harder than a stone cold car should be drriven. What I am thinking, to keep things simple, is to run the Petro Canada 5w40 in the Bonneville. Although it is not a bad price, I think I would rather run less expensive oil. Also, this is just a personal feeling and I have no factual informaiton to back it up, but I think the 40 on the top end might be a little heavy. The other thing I am thinking is to run a dino 10w30, probably Chevron or Pennzoil as these seem to be some of the best dino oils available. I'm not really interested in running a 5w30 dino as the information on this site leads me to believe it will fall out of grade too quickly, but I will consider it if it is suggested to be my better option. If I run the dino, I'm thinking about 2,000 mile changes just due to the type of short trip driving the car will be accustomed to. What do you think would be my best alternative. I appreciate your help. Thanks!