I have a '94 Chev K1500 w/ a 350ci. Just curious which way you all lean towards when it comes to motor oil. Myself on this particular engine I have always used 10w40. On another note, I recently posted a question about my truck. Was having a problem when I cranked the engine to start; it would act as if the timing was too far advanced. ( cranking hardand slow. ) Well After some time I found the problem. It started some time after installing an Accel coil. It's the plain square shaped coil. I fabricated a bracket so I could mount it in the stock location. It was very close to the distributor. Apparently it was causing emf interference causing the erratic timing while cranking. I have now put back the stock coil. The problem has gone away.