People often ask how often they should have a particular service done. It’s a great thing to ask. You can look at your owner’s manual, or have your service advisor look up your vehicle in a service database. What you find is often a surprise to people – there are actually two service schedules.

One is the regular schedule and the other is the severe service schedule. Service intervals are shorter on the severe service schedule. When asked, most folks will say that their driving is normal and that the ‘regular’ schedule probably applies to them. ‘Severe service’ sounds pretty extreme — I don’t drive like that.

Well, here is what the manufacturers say constitutes severe driving conditions; you can draw your own conclusions.

• Most of your trips are less than four miles.
• Most of your trips are less than ten miles and outside temperatures are below freezing.
• The engine is at low speed most of the time – not on the highway.
• You operate your vehicle in dusty areas.
• You regularly tow a trailer or carry heavy loads.
• Drive with a car-top carrier.
• Stop and go driving.
• Driving in very hot or very cold weather.

If that’s severe driving, what constitutes regular driving? Well, it would look something like this: I live somewhere with moderate temperatures all year round – I’m thinking San Diego here. And I live close to a freeway on-ramp. Everywhere I need to go is right off the freeway, at least four miles from my home. I can drive at a steady 60 miles per hour when I’m on the freeway.

I don’t know about you, but that doesn’t sound like my normal driving. It sounds more like ideal conditions. I live somewhere where it gets hot in the summer and cold in the winter. I run short errands around town. Occasionally we load up for family trips.

For me, normal driving includes elements of severe service driving. So here’s what I tell people: think about how you drive, where you live, where you go and what you are expecting to with your vehicle in the near future.

Picture a line with ‘regular’ on one end and ‘severe’ on the other, and make a judgment on where you fall. If your regular oil change recommendation is 5,000 miles and the severe service recommendation is 3,000 – when should you change your oil? For me, it’s closer to 3,000 miles. For my wife, it’s closer to 5,000 miles. Your service advisor will be happy to have this discussion with you and help you sort it out.

Just a quick word on why severe service intervals are shorter. One has to do with heat. That can either be external heat from the weather or engine and transmission heat from stop and go driving or working extra hard moving heavy loads or towing. The heat causes the fluids like oil and transmission fluid to break down more quickly and then they aren’t as effective.

Another factor is water. Moisture naturally collects in fluids as they cool. In your motor oil, for example, if you don’t drive long enough for the oil to fully heat up, the water won’t evaporate. Water in the oil can lead to the buildup of damaging sludge.

If you live where the air is dusty or polluted, fluids will become contaminated and air filters will get dirtier more quickly.

So make an honest evaluation of your driving conditions. You’ve made the commitment to take care of your vehicles, so it only makes sense to follow the right schedule.

Your vehicle manufacturer publishes two maintenance schedules. The regular schedule and the severe service schedule. It’d be wrong for us to tell you that everyone always needs to follow the severe service schedule – but its wishful thinking to say that the regular schedule is always good enough. We’ll give you the definitions and explain the issues, and you can be the judge.

Most manufactures list the following as severe conditions:

• Most of your trips are less than four miles.
• Most of your trips are less than 10 miles and outside temperatures are below freezing.
• The engine is at low speed most of the time – not on the highway.
• You operate your vehicle in dusty areas.
• You regularly tow a trailer or carry heavy loads.
• Driving in very hot or very cold weather.

So think about your typical week. Do you live a block from a freeway on-ramp and enjoy a non-stop commute to work? Or are you like the rest of us where 90% of our trips are on the severe service list?

The answer may be different at different times of the year and for the different drivers in your family. Think of the two service schedules as bookends. Let’s suppose your owner’s manual says the severe service oil change recommendation is 3,000 miles and the standard recommendation is 5,000 miles. You know that you need to change the oil somewhere between 3,000 and 5,000 miles. Look at your driving patterns and conditions and honestly evaluate which end of the spectrum you’re closer to.

If you have a job in a neighboring town and most of your commute is freeway miles, you may choose the regular service schedule for your car. On the other hand, if you live within a few miles of work and only get on the highway a handful of times every month. Something closer to the severe service schedule is more appropriate.

Now why is this so important? Moisture builds up in the engine oil from normal condensation. Short trips or driving when it’s really cold means that the engine doesn’t heat up enough for the moisture to evaporate. The water in the oil leads to oil sludge that gums up your engine and doesn’t let the oil protect it as well. That’s why you need to change the oil more frequently – to get the sludge out before it causes problems.

Towing, heavy loads and very hot weather means that your engine and transmission will operate at higher temperatures and with more stress. The fluids will break down more quickly. Additives that clean and prevent corrosion will be depleted sooner.  Dusty conditions, which may extent also to areas with high air pollution, mean that fluids will get dirty faster and that filters will plug up and won’t work right.

All of these things can lead to premature wear and repairs down the road. They’ll also hurt your fuel economy. If you want some personalized advice, talk with your service adviser. He can help you restore your vehicle to good working order and help you know the best schedule to follow. If you’re not sure, err on the side of protection.

For more great auto tips videos on severe service maintenance, check out our online auto tips videos library from AutoNetTV.

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 oil changes, 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, service 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 service advisor who can help you know which schedule to follow.

Here is what a fleet manager said recently:  “Since city miles are generally tougher on vehicles than highway miles, we use the manufacture’s serve 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 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.