As for long distance - just run it. These trucks were made for long hauls and things fully warm up, seal up, and clean out on long trips.

There are many times I think my truck is going to fall apart driving around town (she's moody) but every year I take two major road trips (3k+ miles) and she just purrs the whole way with no probs.

Let me know where the oil leak is when you find it. What oil are you using?

 

Update on truck is good so far. No mixing fluids or overheating. Washed off engine as well as I could with the fender well still in the way and looks to be just bad valve cover gasket that's now bad enough that its dripping on the exhaust manifold. Still need to get radiator cap checked out or replaced but it is a 16 lb on there right now so its at least the right one. @Ramman18.....I've been using Valvoline high mileage 10-30 for about a year now. Before that it was just regular 10-30 of whatever decent brands. Edit: for the most part I would used regular Valvoline unless I found a coupon for something else

 

Excellent choice on oil! Been using the same but 10w40 since it likes to drink thinner stuff. Can you just tighten the valve cover bolts? I ran mine down a year or so ago. Guess they can loosen over time.

 

I might give that a whirl and see if I can buy some time. That v10 doesn't give you valve cover access to the bolts on the manifold side so I'd only be able to hit the outers. I've been wanting to pull the intake off for a while now anyway so I can get my injectors off and check them out (cant even see 4 of them).