Once a year, you will need to do a rust proofing or also called rust protection service on your vehicle to prevent rusting. Rust spreads really quick on the body of the car and also on moving parts of a car such as door locks, brake cables and power antennas. The under body of a car is most prone to start rusting due to exposure to road salts during the winter and the moisture in the air.
I also saw what happened to the car body parts when not treated with rust protection. This guy had his Minivan broken into by some thieves who used a screwdriver to pop open the front driver and passenger doors. A deep hole was left on both sides of the front doors and he didn't bother to have it repaired. Over time, rust started to form all over that hole and began to spread throughout the body area. When he finally asked for a quote on repairing the damage, they were charging him $600 for both doors. Another guy had his entire fuel line underneath the car damaged badly by rust. It ended up costing him more to repair those parts rather he could have saved money on those repairs, if he had done rust proofing every year.
Rust protection cost about $160 including taxes and it needs to be done only once a year. i like to do it near the end of the month November because this will get my car ready for the coming winter. Those rust proofing guys actually will drill holes over the inner side of the car body near the doors including front, rear and passenger doors. If you are too concerned about them drilling holes on your car body, then rust proofing may not be for you. Roughly, it is about $13 per month which is about the price of about 4 cups of coffee per month. Not a bad investment considering that it helps you safeguard your car from rusting fast.
If you maintain the condition of the body of your car, you will get a higher resale value if you decide to sell your vehicle in the future. You will lower the repair cost as well due to less damage by rust. Once i had a guy offer to buy my car just by seeing the good condition of my car body. He had the same model, make and year of the car just like mine but his car was quite damaged by rust all over the car body. Of course, i refused to sell him my car. I like to go to "Krown" rust protection company and they do a great job of completely spraying rust proofing liquid agent all over the car including areas where it is hard to reach by coating rust proofing. Krown uses oil rust proofing which i believe is more efficient in seeping into the various parts of the car compared to coating rust proofing which only rust proof visible areas where it can reach. They don't have a lot of branches in the city but you can look for their company in your area.