Yesterday I changed out my M1 5w30 which I have been using for all changes for the last 30,000 miles on my 5.3 chevy silverado. I put in the Truck and SUV 5w40 as it has been higly praised so far. I have not had any consumption of the 5w30 in the past. Will using a 40wt over the 30 that was giving me no problems possibley losen up anything that may make the engine start to use some oil? After all GM Specifies 30wt for a reason right??? Am I worring for nothing? Guilt has set in..