Will cheating on the dealer with an independent mechanic void the warranty?

Dear Tom and Ray:

My husband and I have a 2005 Nissan Sentra, and it's time for its scheduled 30,000-mile checkup. Because we still have the warranty, I prefer we go to the dealer and have this routine maintenance done (I hear doing it at an outside garage could cause the warranty to be voided); he would rather take it outside the dealer network. Since we're both students and can't afford to buy a new car, we need to know what the right thing to do is!
-- Preethi

Ray: There are plenty of things for which you absolutely should go to your dealer. Warranty work, recalls and service actions are some obvious ones. Or just good work, if you're lucky enough to have a dealership you like and trust, and that charges fair prices.

Tom: The same goes for unusual problems. An independent mechanic may see two 2005 Sentras a year. So he might not know about something that a dealer, who sees hundreds of 2005 Sentras a year, might recognize immediately. That can save you hundreds of dollars on a diagnosis.

Ray: But scheduled service is something that a lot of dealerships still charge too much for, in our opinion.

Tom: Most 30,000-mile services involve changing the oil and filter, changing the air filter and checking a bunch of stuff. All of the required maintenance items are listed in the back of your owner's manual.

Ray: But it's not unusual, in our experience, for dealerships to add extra services to that list. We've seen 30,000-mile services that cost $400, $500 or $600 when they really should cost only $200-$300. Whatever you decide, having your scheduled maintenance done by a non-dealership mechanic will not void your warranty. As long as you can demonstrate that you have done the maintenance listed in the back of your owner's manual (your repair receipt from any repair shop, or even receipts for parts if you do the work yourself, will suffice), your warranty will remain in full force.

Tom: So here's what we suggest: Show the mechanic the list of required maintenance and ask for an estimate of what it will cost to have all of that work done, using Nissan parts.

Ray: Then call the dealership and ask for its price on the 30,000-mile service. If the prices are the same or similar, then why not go to the dealer?

(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk Web site.)