0w20?




The 0W20 is designed to go with some of the newer engines that have been tested to use it. Your LS1 hasn't.
All of the bearings in your engine require a particular film thickness of lubricant. GM put 5W30, even on the filler cap, for a reason. Unless you feel like using your engine as a test bed for a thinner oil at like temperatures, I would stick with the recommended.
Keep your foot off the floor if you are concerned with fuel mileage...
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I use 10W30 Valvoline Synpower in my Z06.

















