Use to do 3k or 3.7k oil changes with dino, now do 5k changes with M1. Engine in the 99 Taurus is clean metal looking in the oil filler cap, while the 93 was pretty dark with the same +100k miles. The diesel in the truck runs quieter and also seems to run cooler. The 2006 Taurus is getting to end of the factory warranty so I'll probably switch to 5w30 to see how it runs compared to the 5w20. For the gasoline vehicles I look for an A5/B5 oil.