- Nov 19, 2002
- Evansville, IN
I have a Chevy Silverado with a 4.8L Vortec engine. I have been using Mobil 1 5W30. I've heard "good to excellent" reviews on Mobil's 0W40 formula. It seems to be well-engineered for longer drains. My owners manual refuses to recommend anything other than a XXw30 oil. I would like to try the 0W40 for it's long-drain capabilities as well as its higher viscosity. Is the reason they don't recommend any 40 weights simply because of fuel economy, or will the heavier oil damage the engine? The truck is no longer in warranty so that is not an issue for me. Any input would be appreciated.