Make sure your tires are up to pressure - the cold weather reduces pressure.

On your trip, you should check your oil more often - steady driving at speed can use oil more than normal.

Considering your car's age and mileage, your timing belt could be quite old - even if the belt were to break and not do engine damage, you could be passing a big truck at the time.

I do not know what your owner's manual says about the time the belt is good, 850s have a 70k or 7 years - I'll bet that your belt may be on borrowed time.

The Rockies can be a tough test.