My Chevy SBC Engine Burns oil!!?

I have a 1986 Chevy Camaro 305 TBI 5.0L V8. It is all stock with 165,500 miles on it. It has blue smoke that comes out of the exhaust on start-up, and goes away immediatly, unless I really rev it up. Is there any oil additive that WILL work and stop the smoke. I notice that the oil level doesn't change that much though, but like I said, it's just upon start-up and immediatly goes away. I don't want to start changing oils like people say to make it thicker because it will have a terrible time pumping through the pump. Please help. I tried Barrs leaks before but it didn't seem to completly do the trick. It did help a little though...