I have 180K on my 5.7 running 5w/30 and it does not use any oil. It does however have a rear main seal leak. I swithed from 10w/40 to 5w/30 because of an engine knock when cold.
There is a guy on ebay thats make the harness to retro the 95 tahoe to use the 96 HVAC. If anyone would like his ebay store let me know. I bought one. The seller is estradaocc on ebay.