Before going on a long trip, say 10 hours a day, times 2 days at highway speeds, what checks or services should I have performed?
This car is a 2007 Lexus ES350, but I'm looking for an answer that would be useful for any car. Thanks.
Belts. You should carry spare belts in the trunk anyway.
Hoses. Some people carry spare radiator hoses.
Brakes. Unless you don't plan on stopping on your trip.
Battery. Clean crud off terminals and be sure the battery is decent enough to start the car at some rest area in the middle of nowhere at 3am. Check voltage to ensure alternator is functioning fully. Inspect alternator visually for cracked enamel on the little copper wires inside. If enamel is cracked, have alternator professionally checked or consider replacing.
Tires. If one is low, why is it low? Fix the problem. Low pressure will cause the tire to overheat and pop on the highway. People usually learn this the hard way once in their lives. Then you have to unload all your luggage to get the spare out (which is probably flat too, so check it), in the dark, while trucks are whizzing by at 80mph.
If your tires are about bald, you're an accident waiting for a good rain to happen.
If there was ever a time to have the alignment checked, this is it. If the cars pulls ever so slightly to the right, after 10hrs, you'll discover it (and be annoyed by it). In the process of checking the alignment, they will find loose bearings and joints to charge you extra for. The wheels can't be aligned if they are loose.
If you haven't changed your fuel filter in the last couple years, change it. I once logged onto a forum to inform people that after 4yrs of struggling to figure out why my engine sometimes runs hot, I discovered a clogged fuel filter can cause a lean condition and cause an engine to run hot. Instead of thanking me for the tip, they nailed me to a cross for not changing my filter in over 4yrs. Who changes their fuel filter religiously? Exactly. Consider changing it.
At least blow the dust off the air filter and see if you can see light through it. If you've never changed it, consider changing it.
Check for cracks in cv-joint boots. If cracked, replace it quickly before dirt gets inside and grinds the joint to bits.
Oil has been mentioned, but I'll mention it again. Check it.
Check your light bulbs. Always nice to have a cop find an excuse to pull you over in some one-horse town where they have nothing to do but write tickets. Consider carrying spare bulbs. Never touch a bulb with your fingers. The oil from your skin will cause the bulb to blow.
Pack some fuses.
Check your wipers. No fun to be driving forever in the rain with crappy wipers.
Clean windows. Streaks can get annoying after 10 hrs of looking at them.
You could take a flash light, gas can, water bottle (antifreeze), tools (locking pliers, screwdrivers, socket set), jack, lug wrench, lug nut key (as mentioned), a spare tire, drivers license, insurance card (the up to date one),,, where do you want me to stop?
In general, at the very minimum, you will want to check air pressure in tires, and all fluid levels and ensure that they are at the proper levels. Also, checking the condition of the oil and possibly changing it if it is needed (on a trip that long, probably wouldn't hurt to go ahead and do that if it over halfway till the next one anyways). If staying comfortable is a concern, you may also want to have the AC refrigerant level checked as well. Checking the wear on the tires and rotating them if needed would not be a bad idea as well.
All of the above and it doesnt hurt to check the spark plugs. Dirty and worn out spark plugs can dramatically decrease the engine performance and it also affects the fuel consumption.