The manual says to use 5W-30. I read an article somewhere that stated the use of 5W-30 oil was to due to mileage ratings but that 10W-30 offered better shear protection for the engine. Any feedback would be appreciated
5w30 is recommended I suspect due to both fuel mileage requirements and due to its flow characteristics. There have been several threads concerning this issue. But when all else fails, if you run into problems with oil in your ls1 engine, they might question if you are using the recommended oil. If not there might be warranty issues.
Refer to your owner's manual. You will find the recommended oils there, and it does include 10W-30 in the list. Before my first oil change, I did a survey of all the synthetic oils and found that Amsoil 5W-30 had a much better 100 degree C viscosity then Mobil-1 5W-30 or 10W-30. I decided to stay with the 5W-30 but use Amsoil rather then Mobil-1. Amsoil meets all of the required specifications for the Corvette.
Corporate Average Fuel Economy
5w30 is used by virtually all the U.S. auto builders because the EPA will not allow a warm-up period for these tests, and 10w30 costs some fuel economy during cold/cool engine portions of the testing cycle. In my opinion, that's the ONLY reason that they tell us to use 5w30. They HAVE to tell us that when they base all their test on it!
10w30 or 10w40 is definately the way to go for me, especially in warmer climates, (IN MY OPINION)! I manage a very large fleet of vehicles and they run conventional 15W40 motor oil and do quite well, thank you. I run synthetic in all my cars, usually 10w40. Fleets usually can't afford synthetic.
If you used synthetic in your fleet, it would be more economical since you don't have to change it as often. And if you used the dual filter system, most OTR rigs change every 100,000 miles with just filter changes and oil analysis at regular intervals. (Per the
Amsoil brochure) :s