From the owners manual of my 2008 Chevrolet Silverado:
"Use only engine oil identified as meeting GM Standard GM6094M and showing the American Petroleum Institute Certified For Gasoline Engines starburst symbol. Failure to use the recommended oil can result in engine damage not covered by your warranty."
" AS SHOWN IN THE VISCOSITY CHART(5W-30 OIL IS THE ONLY ONE ON THE CHART), SAE 5W-30 IS BEST FOR YOUR VEHICLE. DO NOT USE SAE 10W-40, SAE 20W-50, OR ANY OTHER VISCOSITY GRADE NOT RECOMMENDED."
"IF YOU LIVE IN AN AREA WHERE THE TEMPERATURE FALLS BELOW-20F, IT IS RECOMMENDED YOU USE A SAE 5W-30 SYNTHETIC OIL OR AN SAE 0W-30 OIL."
FROM GARY:
"Hence we have 5w-30 oils ..with no particular exclusive nature to them.. spec'd for the same gas engine that pulls a travel trailer up 6% grades as it is for the sedan that never peaks 100C in oil temp. They just alter the time in service ..something that your commercial service is very sensitive to in terms of costs."
YES, ABSOLUTELY, AMEN, RIGHT ON, THAT IS EXACTLY IT!
If you have an attorney friend that will look at something for you, for free of course, get him/her to actually read the part of the warranty dealing with engine oil. If you have an engine "LUBRICATION RELATED FAILURE" and have the recommended oil, the warranty will cover it. BUT, IF YOUR ENGINE JUST WEARS OUT IN 30,000-40,000 MILES, YOU ARE "NOT" COVERED. The warranty for my Chevrolet even has an exclusion for wear.
I am sure that some of us, "ESPECIALLY ME" over react to some lubrication issues. I have my OCI practices, my filter choices, two brands of oil that I use, synthetic only, and my viscosity preference no matter what the manufacturer recommends. I want what I believe(after study, research, and experience)will give me the longest usable engine life. This has let me average around 200,000 miles(high just over 300,000) before I sell/trade a vehicle. I have never had a lubrication failure and I can't honestly say I have ever completely worn out an engine. Over the years I have had "company cars" where someone else chose and changed the oil and I have had lubrication problems, including one failure at only 50,000 miles. On another, you could turn the engine by grabbing the fan and turning it. Compression was nil. This was back in 1981 and 1984, 10W-30 conventional oil.
It is cold, raining, and the wind is blowing. Perfect weather for working on an amateur radio antenna so that is what I am now going to do.