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Vol. 1, No. 10
October 27, 2002

How To Change Your Oil
by Ken Wilson

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MILEPOSTS Garage Technical Tips

Image: Troubleshooting/Tech Tips Series

The oil in your car's engine is the single most important item that protects it from damage, and ensures many thousands of miles of service. Understand this, and you will find your engine will serve you reliably for many years to come if it's given proper maintenance. Changing your oil is inexpensive, easy, and fast.

There is a right way and a wrong way to change your oil. If you follow the steps outlined here, you can be sure you are doing it the right way, and protecting your engine from damage.

WHAT YOU'LL NEED:
  • Oil (whatever refill quantity is specified for your car)
  • Oil filter
  • Oil drain pan
  • Wrench or socket to remove oil plug
  • Oil filter wrench to remove old oil filter
  • Oil plug gasket (not applicable to all cars)
  • Old rag (clean)
  • Old clothes (you will get dirty)
  • Heavy Duty Electric Oil Change Pump*
*Optional

 1. Check your Owner's Manual for the recommended oil viscosity for the temperatures your engine will be operating under between this oil change and the next one. This will tell you what viscosity to buy. Most Owner's Manuals also indicate how many quarts of oil the engine needs. Most manufacturer's recommend using a multi-viscosity oil; this allows a lighter viscosity when starting a cold engine in cooler temperatures, and a heavier viscosity once the engine warms up to normal operating temperatures. In some climates and under some conditions, a single viscosity oil may be permitted, but the temperature variables aren't as wide as they are for multi-viscosity oils.

 2. Always replace the oil filter when changing your oil. Even though you may not have driven the car much during this time, it's always a good practice to change the oil filter every time you change the oil. If your car is too old to be listed in the specifications books at the auto parts stores, ask at the counter. Most will be able to tell you which oil filters will work on your particular car.

 3. Start your car and warm up your engine slightly. Don't allow it to reach normal operating temperature, but just let it run long enough to circulate the oil well and warm it up a bit. You don't want the oil to be hot, as you risk the chance of being burned. What you are trying to achieve is a balance, as warmer oil flows better than cold oil, and any sludge present in the oil is less likely to be left on the bottom of your oil pan if the oil is drained when warm.

 4. Unplug the coil wire and disconnect the battery ground cable. This is very important, as interruptions can happen while you're working on your car, and you don't want someone cranking the engine once you begin the process of changing the oil. As a further precaution, tape a "DO NOT START - NO OIL IN ENGINE" sign on the steering wheel. Accidents can and do happen, so don't take any chances. Your engine can be ruined in seconds by being cranked with no oil!

 5. Position the oil drain pan, and remove the oil drain plug. Start by removing the oil fill cap on the engine. This will allow better air circulation within the engine block, and will prevent the formation of vacuum, which will slow the draining process. The drain plug is found on the lower part of the engine oil pan. There might be several plugs that look similar, make sure you're removing the oil plug, and not the one for the transmission. The oil plug will normally be closer to the front of the car. Position the drain pan so that when the oil begins to flow out, it will go into the drain pan. As you loosen the drain plug, pressure from the oil may force the drain plug out and into the oil pan. Don't worry, this is not a problem. You might find it necessary to raise the car in order to have enough room underneath to reach the oil plug and filter. If so, make sure you take adequate safety precautions, including placing the car on appropriate support stands, and blocking wheels to prevent rolling. NEVER crawl under a car supported only by a jack! We have found that oil tends to drain faster and more completely when the car is sitting level, so this is preferred if at all possible.

 6. Remove the old oil filter with the oil filter wrench. There are several kinds of oil filter wrenches, the most common type has a band that tightens around the filter as you pull on the handle to loosen it. Others fit on the grooved bottom of the oil filter, and can be used with a ratchet wrench. Determine which would work best on your particular car, and buy that one. The one with the band that tightens will remove almost all filters, whereas the other type might not fit everything. If you have more than one car, consider this before making a purchase.

 7. After loosening oil filter, twist it off by hand. The filter is full of oil, so it will be heavier than normal, and oil will likely come out of the fitting and filter as it's twisted off. You might want to wait for the oil to finish draining from the pan, so you can move the oil drain pan under the filter area.

 8. Important: check the area where the oil filter mounts for the old gasket. Sometimes the gasket on the old oil filter will stick to the mounting surface, instead of coming off with the filter. This is a guaranteed leak, so make sure the old gasket isn't still there. If it is, just remove it with your fingers or a plastic picnic knife. Don't use the flat end of a screwdriver, you don't want to gouge this area.

 9. Allow oil to completely finish draining. Some people even allow overnight, but usually it's satisfactory to wait until you see a slow drip from the oil pan drain opening.

10. Clean oil plug and oil filter mounting. Retrieve the oil plug from the drain pan, if it fell in during removal. A pair of pliers comes in handy for this. With an old rag, wipe off the drain plug and the area on the engine oil pan where it mounts. Also wipe off the mounting area for the oil filter.

11. Install oil pan drain plug. Be careful not to cross-thread this fitting. Also remember it doesn't have to be torqued very tightly. You will have to remove this plug again, and most are threaded to minimize the possibility of leakage. Tighten it enough so that it won't leak, but don't overdo it. Some drain plugs might have a rubber gasket on them. If yours does, make sure it isn't cracked. If it is, you'll want to replace it before reinstalling the drain plug. Your auto parts store should have this gasket available, buy one even if you don't need it now so that you'll have it when you do need it. Store it with your oil filter wrench, so you'll be able to find it.

12. Install new oil filter. Place a small amount of oil on the rubber gasket first, we recommend using fresh oil for this. You don't need a lot, just enough to help it seal. Before installing, prefill the new oil filter. Do this by opening a container of fresh oil, and carefully pour it directly into the filter. Take the mounting angle of the filter when installed on the engine into consideration, and hold the filter at this angle periodically so you don't overfill it. If you do, the oil will run down the sides of the filter as you install it. This isn't a problem, just another clean up chore. When you've filled the new filter, install it on the engine just until the gasket makes contact with the mounting surface. Then, twist the filter an additional 1/2 to 3/4ths of a turn. That's it, don't over tighten!

13. Wipe off any oil on the drain plug and filter. You'll have to check to make sure these aren't leaking, so it's best to clean them up now if you need to.

14. Pour in the recommended quantity of oil. Follow manufacturer's recommendations as to the number of quarts you will need with a filter change. Most vintage V-8 engines require 5 quarts, but there are variations, so check the specifications. After the first quart has been poured in, take a peek under the car to check the oil filter and drain plug. They should not show any signs of oil leakage. This check will prevent you from possibly dumping several quarts of oil on the ground. The chances of this are quite remote, if you've installed everything properly up to this point, but it never hurts to check. When you're through, install the oil fill cap.

15. Clean the battery ground, and reattach to battery. This small bit of preventive maintenance will ensure reliable starts and bright lights. Next, check the dipstick. It should show "FULL". If it doesn't, go back and check how many quarts of oil you've poured in (count the number of empty containers). If the quantity is correct, allow a few more minutes for the oil to settle in the oil pan and recheck. If it doesn't show "FULL" at this point, you might have the wrong dipstick for your engine. Since you know the quantity of oil is correct, jot down somewhere the point on the dipstick that the oil level comes to when full, and add a correct dipstick to your list of parts needed. Use this note as a reference when checking the oil level until the correct dipstick is available.

16. Crank your engine for a few seconds. Do this without reattaching the coil wire. This will give your oil pump the opportunity to start circulating oil without the engine starting. You may repeat this process a couple of times, if you wish. Then install your coil wire and start the engine. Watch the oil pressure warning light or oil pressure gauge. The light should go out in a few seconds, and the gauge should start showing pressure in a few seconds. You might hear the lifters tapping for a few seconds as well. This is normal until your engine pressurizes the oil passages and circulates the oil. This should not last for more than a few seconds. If it does, or if the light fails to go out or your oil gauge doesn't show pressure, turn off the engine. Check for leaks and verify correct oil level. Do not continue to operate the engine under these conditions. You may only have a malfunctioning sending unit, but you won't know until you test the oil pressure with a manual gauge. If the oil level is correct, and there are no leaks, chances are very remote you've done anything wrong to cause low oil pressure.

17. With engine running, look for leaks under the car. Check your oil filter and oil drain plug again. You should not see any signs of oil leaking. If you do, stop the engine and tighten enough to stop the leak. Also keep an eye on the ground underneath the car for a few days, to make sure you haven't developed a new leak.

18. Dispose of your used oil and filter properly.
There are restrictions in some communities as to what type of containers used oil can be transported in, as well as specific requirements on handling used oil. If in doubt, ask at the auto parts store where you purchase your oil. It's important to know the facts beforehand. Most auto parts stores have a program in place to recycle or dispose of used oil and filters. If yours doesn't, find one that does. Recycling used oil is good for the environment, and may be a requirement in certain areas.

At this point, you have successfully completed an oil and filter change. The fresh oil and filter will start removing dirt, sludge, and deposits from your engine immediately. As you check the oil level over the next few weeks, watch for signs of the oil becoming dirty. If the oil turns black and is no longer transparent on the dipstick, make plans to change the oil and filter again soon, even if you haven't reached the mileage or time interval for changing the oil. This shows that your engine is dirty, and more frequent oil and filter changes are warranted. Continue to change the oil and filter more frequently until the oil remains transparent for a mileage interval or time period closer to the regularly scheduled changes. By doing so, you are ridding your engine of the damaging sludge and other deposits that cause excess wear on vital parts. This is especially true of engines that have sat for long periods of time without being run.


Automotive Mileposts recommends this Heavy Duty Electric Oil Change Pump. It's battery operated, and makes changing fluids in your car very easy. It saves wear and tear on you as well as your car.

Copyright © 2002 Automotive Mileposts, Inc.
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