A lot of Chicago drivers have asked whether or not they should use their severe service maintenance schedule, which is listed in their vehicle's  owner's  manual. It can be somewhat confusing, so we decided to consult an expert. Cricket Killingsworth is from QMI/Heartland, a manufacturer of automotive products and fluids. She's been in the automotive business for over 30 years and is a speaker, a trainer and a writer.

Cricket says there's so much confusion on this topic because, "Most owner's 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."

Foreign and domestic vehicle manufacturers create a specific schedule for each vehicle they manufacture. So there isn't one generic schedule that applies to all vehicles. In addition to your owner's manual, Chicago automotive repair centers (including Tuffy Chicago (Diversey Pkwy)) subscribe to information services that provide the auto maintenance schedules for every vehicle - so they can help Chicago drivers know when to take care of needed services. Below is a typical definition for severe service.

• Most trips are less than four miles/six and a half kilometers
• Most trips are less than 10 miles/16 km and outside temperatures are below freezing
• You drive regularly in very hot Illinois weather
• The engine is at low speed most of the time (not on the freeway)
• Stop and go driving
• You drive in in dusty or muddy conditions
• You routinely tow a trailer, haul heavy loads or carry a car-top carrier around Chicago

It's common sense for Chicago drivers: Just a few minutes at higher speeds allows the moisture in the oil to evaporate. Very short trips, or trips of less than 10 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 break down faster. Dusty and muddy driving around Chicago 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 habits. Look at your owner's manual or talk with your Tuffy Chicago (Diversey Pkwy) 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 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 Illinois highway driving in moderate weather, you'll likely have a fairly good amount of severe service mixed in. Some Chicago drivers just want to play it safe and follow the severe service recommendations, rather than analyzing how they drive each month.

Ask us for help evaluating your driving and service needs.

Tuffy Chicago (Diversey Pkwy)
1400 West Diversey Pkwy
Chicago, Illinois 60614
773-929-3622