Why Cold Weather Hurts Your Truck’s Gas Mileage
It’s that time of year again – colder temperatures are coming. During the winter time, most truck owners notice a 5-10% drop in fuel economy. Since truck fuel economy is already pretty low, going from 16 MPG to a little better than 14 MPG means an extra $25 to $50 in extra gas every month…and most truck owners notice that right away.
It’s frustrating, but it’s something most truck owners have learned to live with. However – there are some things you can do about lower gas mileage in cold weather. First, though, we have to know why it happens.
The most common explanation you’ll hear for the drop in gas mileage is that it’s caused by a “winter blend” of gasoline. While there is a slightly different formula of gasoline sold during the colder months, that’s not the problem. The answer is the cold itself.
Within 30 seconds of starting your truck, the engine computer begins checking the temperature of the air entering the engine. This measurement is important because it determines if extra fuel is needed to prevent a lean condition. [For those that don’t know, “lean” refers to a situation when there isn’t enough fuel being used in the combustion process. Without getting too technical, a “lean” condition is bad because it can cause engine damage.]
The intake air temperature has a direct impact on whether or not an engine will run lean. If the air is very cold, it doesn’t mix properly with gasoline (gasoline atomizes poorly in cold air). Therefore, if your truck’s computer detects cold air, it injects too much fuel (called a “rich” condition) to prevent any possibility of your engine running lean.
Once the engine has reached full operating temperature, the air in the intake is significantly warmed by the heat radiating from the engine compartment. At this point, the engine computer returns to normal and stops using extra fuel. So, the sooner you can warm-up your engine, the better your fuel economy will be in the winter time.
Here’s what you can do to get your cold weather fuel economy back to normal:
1. The easiest solution is to park your vehicle in a heated garage. If you can prevent your engine from getting really cold, you will decrease the amount of time it takes the engine to get nice and hot.
2. Use a block heater, especially in colder climates. Block heaters aren’t technically necessary in most climates in the continental United States, but anyone who has used one will tell you they cut engine warm-up time substantially.
3. Don’t sit and warm-up – start driving right away. When it’s really cold outside, a lot of vehicle owners let their engines run for a few minutes before taking off. However, this “warm-up” really hurts your gas mileage. It’s also bad for the environment, and contrary to popular belief it’s not “good” for your vehicle either.
Bottom Line: Even if you can’t park inside or use a block heater, eliminating extended “warm-up” idling will make a BIG difference in your gasoline bill.
Filed Under: Maintenance Tips