98 f150 4.6. I just run a thick oil in the summer heat so it doesn't thin out as much. Just high mileage. I figured the shell isn't as thick as the 20/50 so why not. I just wanna make darn sure I'm not gonna screw my engine up but engines don't know what kind of oil it is they just know it's oil...
So my question is this. I've heard a lot of people use shell in there gas engines because it keeps things clean and is a really good oil. I mean 15/40 isn't that heavy of an oil. I use 20/50 conventional oil in the summer time because of my high mileage. Other than different additives what's...