Interesting post. We have a 2018 Highlander. I dumped the factory fill around 2,000 miles, and ran that new fill on up to the 5,000 mile car mark, making the 2nd run about 3,000 miles. No issues. Have been using Amsoil XL0w20, with Amsoil filters. Since then, I've gone 5,000 miles on the same...