Oil Changes
What does oil do?
Oil lubricates, protects, cleans and cools your engine... HOW? lubricate engine components so that they will easily pass by one another without a significant loss of power due to friction. Of course, at start-up, this is especially true. As an engine sits, oil tends to run down into the oil pan. Therefore, when the engine is started, the oil must be quickly pumped throughout the engine to provide sufficient cranking speed for the engine to turn over. By keeping engine components from coming in contact with each other, motor oil also provides protection against wear. If an engine does not remain clean, it does not remain efficient. Deposits within an engine gum up the works and reduce fuel efficiency while robbing your engine of performance. In addition, contaminants within an oil that are left "unguarded" can cause incalculable wear within an engine. Motor oil is responsible for a large percentage of the cooling that takes place within your engine. Your radiator (anti-freeze system) is only responsible for cooling the upper portion of your engine. The rest (crankshaft, camshaft, timing gears, pistons, main and connecting rod bearings and many other critical engine components are cooled mainly by the motor oil within your engine.
What is involved in an oil change?
The general oil change procedure has really not changed over the years. It usually involves jacking up the car, and draining the oil from the bottom of the pan. Remove and replace the oil filter. Check your manual to see what the capacity is for an oil and filter change, as well as the proper oil type and viscosity. Remember, many European brands have very specific oil requirements for later model cars. Add the oil, start the engine and let it run for 20 seconds or so.
Shut off, let the oil settle for a couple minutes, and recheck the level. Aim to have your oil level around the mid to ¾ point on the marked area. DO NOT OVERFILL. This is as important to engine safety as under filling an engine.
Be sure to record your maintenance either on the maintenance card or in a log and store it with your car.
How often should I change my oil?
Most vehicle manufacturers recommend changing the oil once a year or every 7,500 miles in passenger car and light truck gasoline engines. For diesel engines and turbocharged gasoline engines, the usual recommendation is every 3,000 miles or six months.
If you read the fine print, however, you'll discover that the once a year, 7,500 mile oil change is for vehicles that are driven under ideal circumstances. What most of us think of as "normal" driving is actually "severe service" driving. This includes frequent short trips (less than 10 miles, especially during cold weather), stop-and-go city traffic driving, driving in dusty conditions (gravel roads, etc.), and driving at sustained highway speeds during hot weather. For this type of driving, which is actually "severe service: driving, the recommendation is to change the oil every 3,000 miles or six months. For maximum protection, most oil companies say to change the oil every 3,000 miles or three to six months regardless of what type of driving you do.
A new engine with little or no wear can probably get by on 7,500 mile oil changes. But as an engine accumulates miles, blowby increases. This dumps more unburned fuel into the crankcase which dilutes the oil. This causes the oil to break down. So if the oil isn't changed often enough, you can end up with accelerated wear and all the engine problems that come with it (loss of performance and fuel economy, and increased emissions and oil consumption).
What could happen if I don’t change my oil?
If motor oil is not changed, it gets dirty. If the car has a lot of miles on it, the piston rings may not be as tight as needed, and blow-by gets into the crankcase, which over time dirties the oil. It then makes the oil thicker. Crud in the oil sticks throughout the oil galleys. Once the oil galleys become clogged, the oil cannot drain back down through the engine into the oil pan. The oil builds up in the valve covers, which means there is less oil in the oil pan. Once the galleys are plugged, the bottom of the engine "runs out" of oil (since the oil can't get back down into the bottom). The bearings will seize and the engine will stop running.