It was interesting they called out Amsoil and Royal Purple in here as "Good quality synthetics" in a mainstream article like this next to ginormous brands like M1. https://www.wheels.ca/news/48850/
I did this with all my high milers...
MECHANICALS: Keep it lubed: On the mechanical side, I always use top-quality synthetic lubricants in the engine, transmission and differential. I started this trend when my Volvo was new and the oil I opted for was Mobil 1. These fully synthetic oils such as Mobil 1, Amsoil, Royal Purple, Pennzoil Platinum etc. offer better thermal stability, cold temperature flow, consistent viscosity and zero sludge forming compared to conventional oils. This meant I was always getting excellent lubrication of all the critical moving parts while improving my fuel economy. Even though this was a more expensive choice than conventional oil initially, in the long run it saved me money with less wear and tear. Oil change intervals can be extended when you use synthetics due to their superior properties. This will help overcome the extra cost of the oil itself. Always check with your vehicle's warranty schedule when determining your oil change intervals.