I changed my factory fill at 1100 miles. Went with M1 [email protected] 5W-30 with a M1 113 oil filter. Now at 5K miles it runs beautiful and burns no oil. I have %19 left on the OLM so its going to be change time soon.
My 02 Camaro SS LS1 came FF with M1 5W-30.
These new Gen IV 5.3L's are awesome engines. I love mine. Very powerful with the #243/799 LS2/LS6 cylinder heads. Also the most fuel efficient out there. I've knocked out 20-21MPG @ 70 on the Interstate a dozen times.
I have 92K on my 5.3L I bought it used over a year ago. I run Max life I have no oil leaks or consumption good luck with your truck. I figue with 92K on my truck why start running synthetic now..