Buying my first Semi Truck?

You have no experience in trucking, DON'T DO IT! You are not ready, as proven by your question. You need to have at least 6 months of household expenses (not truck expenses, but your regular bills) set aside. And why not drive for a company first? You can learn on someone else's dime, keeping records on their truck just as if it were yours would teach you what to watch for. Learn the productive lanes, load securement, proper routing, and the regulations all at someone else's expense. Not to mention working for a company will help you get health insurance at an affordable cost also. If you go shopping for a truck and the dipstick shows milky brown oil, what does it mean? How well do you know the hours of service regulations? Back to your original question, that can't be answered unless you know what you will be doing with the truck. For some jobs a mid-size would be good, different gearing for different vocations, single axle or tandum, sleeper or day cab?

Would recommend Tony's Toys &Trucks 707-569-7000 they have LOTS to choose from---

Have a close look at any truck with Scania on it.

Concentrate on obeying the road rules, and DON'T drive

when dog-tired.

Perhaps you should ask your trucking buddies. Most engines can run 500,000 mi without much work if they were cared for. I would think that 250,000 or less miles would be a good start.

You are a lot better off talking to your owner operator friends than anybody on here.

What do you plan on hauling? Vans or decks? Or will you be off highway? Long haul or day trips or city? What sort of weights?