1991 Chevrolet K1500, 4.3 V6, 116k miles (estimated, due to broken odometer). Has had bad valve stem seals since I purchased it five years ago with 89k miles. Always a blue puff of smoke on startup. I can't tell if it is smoking badly now. Lately, it is starting to use a lot of oil. A quart every few months. I don't know if this could be from the bad stem seals, or if rings are getting worn? I might mention that this vehicle is a short tripper. I was doing once-per-year oil changes. Thinking I am doing about 6k miles per year or less. Decided I will start doing twice-per-year oil changes due to the short trips. Wondering if a 40 weight oil will reduce consumption. I've been using a 5w/30 as spec'd (although I put 5w/20 this last oil changed because that's what I had on hand). Thinking of going to a 5w/40 or 10W/40, for summer. Maybe even a 15W/40. Thoughts and suggestions welcome.