Can you use 5w20 instead of 5w30 engine oil when they reccomend 5w30

Use only the oil weight on the oil cap or owners manual if the cap does not list the oil weight. Most older vehicles called for eather 10w30 or 5w30 depending on the ambient temp. In the past 10 or so years, manufacturers updated engines for better fuel efficiency by tightening tolerances in the engines, thereby needing a lighter oil weight to provide sufficient lubrication for the parts So manufacturers started requiring 5w20 oil in their engines. I work as an Auto Care Technician at Walmart, and we will NOT do an oil change for any weight other than the recommended weight by the manufacturer. If it calls for 5w20, we use 5w20, regardless of what the owner wants. This is to avoid any possible engine oil related problems. People will blame someone else if they have a warranty issue the dealer refuses to honor for whatever reason, and it would go back to the last place the vehicle had the oil changed at. So therefore at Walmart, we follow the manufacturers recommended oil weight for all oil changes.