Dear Tom,

I own a 2008 Chevy Malibu. Is it necessary to warm up my car for up to 20 minutes before driving it? My father told me I should because the engine could stall and/or get damaged. Thanks for your advice?

Celene from Buffalo, NY


Running your car to warm the engine before driving is no longer necessary. Today's cars have computer driven performance systems that compensate for outdoor temperatures and cold engines. You can head out after just a couple of minutes of running the engine in the morning or after the car has "sat" for a few hours. I can understand your father's concern with the cars of old, but today's technology has eliminated the need for a thorough warm-up before driving.

Celene brings up a valid concern. In days of old, cars needed to be warmed up before driving for a number of reasons:

• Primitive fuel delivery systems (carburetors)
• Low voltage, no self-adjusting ignition systems
• Poor lubricants

Let's look at each point in a little more detail.

Fuel Delivery Systems

Year ago the fuel delivery systems used a carburetor. This device mixed the fuel to make it suitable for combustion in the engine. It was an entirely mechanical process. When cold, an engine requires a rich fuel mixture to start. A cold start circuit was built into the carburetor in which the opening and closing of a valve was controlled by a spring that expanded when heated and contracted when cold. The spring was connected to the carburetor choke valve so when it was cold outside, the spring contracted and pulled the valve closed and airflow was restricted. With less airflow, more gas was sucked into the carburetor, resulting in a richer fuel mixture needed to start a cold engine. As the engine warmed up, the temp-sensitive spring expanded and pulled the choke valve open to allow in more air for a leaner fuel mixture (a warm engine condition). Today, through the use of electronic sensors, computer-controlled performance systems measure both the outside air and coolant temperatures and adjust the fuel mixture accordingly (electronic fuel injection system).

Ignition Systems

Before computer technology, ignition systems generated low and inconsistent spark output. They were comprised of a spark distributor, points, plugs, condenser, rotor, distributor cap, ignition coil, and wires. There were hard settings of ignition points and there was very little self-adjusting function. Today's ignition systems are electronically controlled and thus entirely self-adjusting. In most cases, the distributor, points, condenser, rotor and cap have been removed and replaced by an ignition module, ECM (Engine Control Module) and multi-function coil. The system automatically adjusts itself based on environmental conditions and the demands placed on the engine. Plugs last much longer and burn hotter than they used to, and systems operate trouble free for thousands of miles.

Poor Lubricants

Starting a cold engine used to be hard on engines. Lubricants simply did not flow very well when they were cold, resulting in dry mating surfaces (surfaces that come in contact with one another). Consequently, lubrication of these surfaces was extremely important immediately upon start-up. It was the accepted rule of thumb to warm up the engine before driving a vehicle. Lubricants have come a long way in the past couple of decades. Chemical additives have been developed and used to produce lubricants that can maintain their viscosity (flow rate) in all temperatures and under the harsh and volatile conditions of the internal combustion engine. I have no problem heading out shortly after a cold start IF the oil and filter have been changed according to manufacturer's specifications. If engine oil has not been changed according to specs, it loses viscosity (ability to flow adequately). What causes this viscosity breakdown? The chemical additive package breaks down causing the oil to stop flowing adequately so the oil can't do its job of lubricating, which increases friction between parts. Friction produces heat in critical internal engine parts as well as the wearing away of surfaces. The ultimate result is premature engine failure. Pass the wallet, please.

Read More Stories from Tom Torbjornsen:

- Oil Change Every 3,000 Miles?
- Keep Your Car Young
- Synthetic Motor Oil: Should You Use It?

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