A lot of our viewers have asked whether or not they should use their severe service maintenance schedule, which is listed in their car owners' manual. It can be confusing. Let's clear the air on this subject. Cricket Killingsworth is from QMI/Heartland, a manufacturer of automotive products and fluids. She's been in the automotive business for 20 years and is a speaker, a trainer, and a writer. Cricket says there's so much confusion on this topic because, "Most owners' manuals actually have two maintenance schedules. Sometimes these are called 'regular service' and 'severe service'. Sometimes they're simply called Schedule 1 and Schedule 2. A severe service schedule recommends that things like an oil change, air filter replacement, and transmission service be done more often: either in fewer miles or in less time.

Manufacturers create these specific schedules for each vehicle they make. So there isn't one generic schedule that applies to all cars. In addition to your owners' manual, Denver automotive repair centers subscribe to information services that provide the maintenance schedules for every vehicle - so they can help you know when to take care of needed services. Below is a typical definition for severe service.

• Most trips are less than four miles
• Most trips are less than ten miles and outside temperatures are below freezing
• You drive in very hot weather
• The engine is at low speed most of the time (not on the highway)
• Stop and go driving
• You operate your vehicle in dusty or muddy conditions
• You tow a trailer, regularly carry heavy loads or carry a car-top carrier

It's common sense: Just a few minutes at freeway speeds allows the moisture in the oil to evaporate. Very short trips, or trips of less than ten miles when it's very cold, don't allow the engine to heat up enough to get rid of the water. And water in the oil leads to damaging sludge. Also, towing and heavy loads raise operating temperatures and cause fluids to breakdown more quickly. Dusty and muddy driving means that more dirt will get past the air filter to contaminate the fuel system and engine oil.

The bottom line is that you need to decide for yourself if the regular or severe service schedule is right for you, based on your driving. Look at your owners' manual, or talk with your Addison Auto Repair & Body Shop service advisor who can help you know which schedule to follow. Addison Auto Repair & Body Shop is located at 2005 S. Holly Street, Denver Colorado.,

Here is what a fleet manager said recently: "Since city miles are generally tougher on vehicles than highway miles, we use the manufacturer's severe service schedule as the basis for our preventative maintenance program. We massage those schedules over time, increasing or decreasing the service intervals so that they make the most sense. There is a little bit of art to go along with the science.

Make an honest evaluation of your driving habits. Unless you do mostly Colorado highway driving in moderate weather, you'll likely have a fairly good amount of severe service mixed in. Some people just want to play it safe and follow the severe service recommendations, rather than analyzing how they drive each month.