Not knowing what kind of engine is in your truck is a serious handicap, and not caring is a bigger one. You are going to honestly tell me (or a DOT officer) that you've performed a thorough pretrip when you can't even tell what that big lump of metal under the hood is?
I sure hope this sort of apathy doesn't extend to tires ("they're black, round and seem to hold the rims off the ground so I don't care") or brakes ("Well, the truck stopped just fine when I pulled into the truck stop, must be ok"). But, given the quality of CDL mill drivers lately, I doubt it.
You would think sooner or later words like Cummins, Detroit or Mercedes would jump out at you even by accident when checking your oil IF you ever do. Reminds me of a goofball friend of mine I was doing a brakejob for on his explorer. Took him to advance auto to buy the parts and the girl asked him if it was 4 wheel or 2 wheel drive. He didnt know. This guy is in his 40s. I inconspicously snuck down one of the aisles and pretended I didnt know him.