I'd like to talk about how often you change the oil in your vehicle. If you look in your Owner's Manual, it will most likely recommend changing the engine oil every six months or 7,500 miles under normal conditions, and every three months or 3,000 miles under severe conditions. But what are "normal" conditions? And do you actually drive "normally"? And what are "Severe Service" conditions?
"Severe Service" Conditions Defined...
Let's look inside some of the service manuals and see what the automakers consider "Severe Service". The term "Severe Service" is defined as operating the vehicle under any of the following conditions:
- Frequent short trips driving less than 5 miles (8 km)
- Frequent driving in dusty conditions
- Extensive idling
- Trailer towing
- Sustained high speed operation
- Off road driving
- Desert operation
- Frequent starting and stopping
- Cold climate operation
- Short trip operation at freezing temperatures (engine not thoroughly warmed up)
- Commercial service
- Stop and go driving
Hmmm.... Seems to be like the way I drive. How about you?
"Normal Service" Conditions Defined...
The definition for "normal" service is easy, and I quote, "Refer to Normal Maintenance Schedules only if none of the conditions from the Severe Maintenance Schedule are true".
Indicator Based Service...
Okay you say, that's fine. But my car has one of those "Change Oil" lights. This light comes on based on the time and miles driven and the conditions you have driven the vehicle. My experience with them is that they are little more than a fancy odometer. Maybe I'm old fashioned, but I don't think I want to trust the health of my engine to a light. What if the bulb is burnt out? What if I forget the last time it was on? In the service manual it says if the light doesn't come on within one year, to change the oil anyway and reset the light. It also says the oil should be changed once a year or every 10,000 miles, whichever comes first. Change my oil once a year?!?!? Not with my car!
Your Oil Filter...
Did you know that most automakers recommend replacing your oil filter every other oil change, or once a year, whichever comes first? I snatched this out of a GM service manual:
Replace
Engine Oil: Every 7,500 miles or 12 months or when "Change Oil" light comes on. If equipped.
Oil Filter, Engine: At first, then every other oil change or 12 months.
That may have been okay when oil filters were huge affairs that held a quart of oil. These days when everything in a car is downsized and made lighter to save fuel, an oil filter barely holds a pint. Now a smaller oil filter has nowhere near the filtering capability of its larger ancestors, so that would mandate more frequent replacement.
The Bottom Line...
The best thing you can do to prolong the life of your engine is to change the engine oil! You invested $30,000.00, $40,000.00 or even $50,000.00 in your vehicle. Doesn't it make sense to do whatever you can to prolong its life? If you change the engine oil and oil filter every three months or 3,000 miles, you make it almost certain that your engine will run at its best for a couple of hundred thousand miles. It's certain that you will replace timing belts, water pumps and alternators over the life of your vehicle. These are relatively cheap and easy to replace, but the engine itself is expensive and difficult to replace, and whatever you can do to prevent it surely must be worth the cost. And if you have a diesel engine, that 3,000-mile interval is almost mandatory under any condition.
