Hey Scotty,
I have a 2001 Toyota RAV4, 2.0 L 4 cyl engine with 225,988 miles on it. Bought it in 2018 with 188,000 miles on it, but I have been using 10W30 full synthetic high mileage oil instead of 5W30 synthetic oil. I don't think the engine has any or much wear, I have been doing oil changes every 5,000 miles or less. My only worry is here in Chicago, during the winter with the oil getting thicker with the cold temperatures and dry starting the engine causing more wear. Should I start using 5W30 synthetic oil or continue using 10W30 synthetic high mileage / 5W30 synthetic high mileage oil?
Use the oil viscosity that is recommended in your manual. Also check for bulletins or charts that retroactively recommend oil viscosity from Toyota themselves. Some cars, only one type of oil is recommended. Others, several types of oil are recommended. Use what is recommended in the manual, and/or the updated viscosity by Toyota.
The Toyota owner's manuals are pretty good about giving you the correct weight oil based on the ambient temperature. Check yours. I use 5w30 in winter and 10w40 in Summer, per my owner's manual.
As for “high mileage” TBH I don’t know. I am more concerned with viscosity than the actual marketing names of “high mileage”. I have 300,000+ miles on my Prius. And I just use the viscosity that is recommended.