Can spark plugs really last as long as 100,000 miles?
That would be pushing them to their limits. Some spark plugs may seize after just about 60,000 miles. Seized in cylinder heads, it may take a 4-hour work just to have them removed. And sometimes, the cylinder heads even have to be disconnected to get work done on the plugs. It can take a lot of work to repair seized or damaged spark plugs. So even if they continue to fire, you shouldn't ignore the plugs and let them run for as long as they can. You should check them for wear and to determine their overall condition. Some plugs don't even last longer than 30,000 miles. If they're inspected regularly, then you can spot the problem early on. You can have them replaced even before they foul up badly and mess up the vehicle ignition system.
I'll be away for a while. How can I make sure that my Subaru DL will still be in good running condition when I get back? It will be in the garage for an extended period.
Ask someone to start the vehicle or drive it at least every 3 weeks. It should be warmed up to operating temperature every once in a while or at least once a month. This will ensure that the gaskets and other seals won't dry up easily. Before you leave your car and keep it in storage, check up the car systems to make sure that everything is running well.
If I load some extra weight on the vehicle, should I put in more air in the tires? Will this help?
Putting in more air pressure in tires will help them adjust, adapt, or cope with the extra weight on the vehicle. Consult the owner's manual for manufacturer recommendations. In some cases, about five pounds can be added to the recommended pressure by the manufacturer. However, this doesn't mean that the vehicle could and should be overloaded. Excessive loads on the vehicle can make the tire cord break. This can also lead to heat building up because of unusual sidewall flexing.
Why do they say that you should kill the engine or turn off the vehicle if you'll be idling for extended periods? What can go wrong?
If you let the engine idle for minutes or for an extended period, the vehicle will consume more fuel compared to starting your vehicle. That's why some would advise you to refrain from idling excessively and to instead switch off the vehicle if you'll be waiting or stopping by for several minutes.
Why do they say that you shouldn't cover the vehicle during winter? How come some people claim that it's not a good idea?
Some covers may not provide the desired protection for the vehicle and instead trap moisture. If moisture is trapped for an extended period, this can lead to rust buildup. Some would then suggest that you use a fan to blow air onto the car and prevent moisture from setting in.