Automobile Repair/Oil change

Performing an Oil Change

Changing your auto's oil regularly is essential to your engine's proper operation. As dirt and metal filings build up in your car's oil it becomes less able to provide proper lubrication. With time your oil will degrade, causing Viscosity to increase, further limiting its ability to lubricate the engine. This guide will not get into specifics for each model of auto, more info can be found online and in the various brands of repair manuals available.

In recent years, both the metallurgy of engines and the chemistry of oil have seen great advances, so that many engines outlast the rest of the car without need for major overhauls or rebuilding, if given proper scheduled lubrication.

Car manuals state the recommended oil service interval for the car; there are often a specification for easy duty and one for heavier duty. Contrary to what is sometimes assumed, sustained operation at higher power levels and higher temperatures constitutes easier duty, as far as the oil is concerned, as it allows any contamination of water vapor and/or fuel to boil off. Thus, engines which are mostly restricted only to short usage in the city will require more frequent oil changes due to the buildup of these contaminants. Extreme high temperatures, however, will cause normal oils first to deteriorate, then to "carbonize", i.e. turn into hard solid carbon particles, with bad effects on lubricated parts; this generally is only a problem in engines which badly overheat, or in the bearings of turbochargers which do not have mechanisms to prevent this, such as water cooling for the bearings, or systems to continue to pump the oil after engine shutoff. In these cases, in addition to more frequent oil changes, use of synthetic oil, which is more stable to high temperatures, may be of advantage.




  1. Basic Socket set and Ratchet. Almost any basic socket set 3/8in drive will have the proper size for most cars and light trucks.
  2. Oil of the correct type for your auto. Your car's manual will list the proper type and amount of oil to use.
  3. Oil filter. Someone at the auto parts store will help you find the correct filter for your auto. Quality of filters varies widely, in terms of quality and amount of filtration material as well as quality of such internal components as bypass valves, and much debate is documented on Usenet and the Web regarding analysis of the internal components of various brands.
  4. Something to catch the used oil. I use an old kitchen pot, but car parts stores sell suitable alternatives.
  5. Oil filter wrench.
    1. The "strap type" looks a bit like a large egg frying ring with a handle, and wraps around the filter body and tightens its grip as it is twisted, somewhat similar to kitchen gadgets sold for opening tops of jars. It often has two separate settings for wide and narrow filters; however the wide range of filters used currently does not guarantee that either of these settings on a given wrench will fit, so a few sizes of this type of wrench are available. The handle may be fixed in the plane of the strap, or swivel to allow angled access in tight areas.
    2. The second type of wrench is the "cup" type, which fits over the end of the filter, which usually has several flutes pressed in, and in turn attaches to a socket wrench. This type of wrench comes in several sizes which must be fit to the particular filter.
    3. It is also possible to pierce the oil filter with a screw driver and a hammer if you do not have access to any tools.


  1. Ramps or jack stands. You may find it more comfortable to purchase some ramps or jack stands to raise the auto a bit off the ground while you work. Proper use of these is outside the scope of this how-to, but be sure to follow all directions and warnings.
  2. Cardboard. Also, I use a large piece of cardboard to keep my back out of the dirt when working under the car. It will also prevent ugly oil spills on the floor.
  3. Sealing ring for the drain plug. It's a good idea to replace the copper or alu sealing ring of the drain plug. Again, the auto parts store will help you.

Changing the Oil


Step 1: Removing the old oil


Firstly run the engine on idle for a few minutes, This makes the oil warm which will let it drain from the sump faster. After turning off the engine, get under the auto and locate the oil pan, usually directly under the engine. At the base of the oil pan there will be a drain plug. Position the bucket/pot/etc. you decided to use for old oil below and in front of the drain plug. Remove the drain plug with the ratchet and socket set. Allow the oil to drain completely. Replace the drain plug, preferably with a new sealing ring.

There are two schools of thought regarding draining the old oil; one believes in letting the oil drain for a long time so as to extract as much of the old, presumably dirty and contaminated oil from the oil passages as possible. The other philosophy is the opposite; to complete the entire operation in the shortest possible time, in order that there be some residual oil still present in the oil passages to provide some lubrication during the period while the oiling system (including the filter) must refill, on the grounds that, if the oil is changed on a reasonably frequent schedule, a few ounces of contaminated oil in the new oil for the next few months are preferable to a few seconds of oil starvation.

Step 2: Removing the old oil filter, and installing the new one


Locate your auto's oil filter. Position a rag below it, as some oil will come out as you unscrew it with the oil filter wrench. Unscrew the old oil filter, and put it aside. Lubricate the seal on the new oil filter with a few drops of oil. Check the old filter to ensure that the seal is still there and did not stick to the engine, as happens occasionally and is easy to miss; in such a case, the new filter will not seal correctly and chronic major oil leaks will result. Then screw it on until it starts to get tight and then just 3/4 of a turn more. This ensures the filter will be properly seated with out over-tightening it. Since a properly installed filter will become slightly more tightly sealed over time as the gasket swells somewhat, an overtightened filter can become a major problem to remove, with strap type wrenches slipping before the filter turns and cup-type filters actually breaking before the filter loosens.

Step 3: Refilling with new oil


Locate your auto's oil fill spout, generally on the top of the engine somewhere. Take the top off, and fill with the amount of oil specified in your auto's manual using a funnel to avoid spilling. Replace top. If you're like many people and don't have a manual and you were able to fill the oil filter, go ahead and fill the engine until the oil is level with the full line on the dipstick. Start the engine and let idle for a few minutes, then shutoff the engine, wait a few minutes for the oil to drain into the sump, and check the dipstick to make sure the oil is at the proper level. Always check the oil with the engine off unless the dipstick says otherwise. Do not overfill or underfill. Remember to dispose of your old engine oil correctly at your local waste recycling center.

Step 4: Remember your oil change


Note down the mileage and date of the oil change, so you know when to change it the next time.

  1. you'll often find a small paper "next oil service" near the engine
  2. in the service booklet - if it's not already lost (very recent cars only have an electronic service "booklet" located at the manufacturers computers)
  3. "modern" cars also have an electronic service reminder, which can be reset with a special dashboard button sequence and/or electronically through the OBD connector.

But remember that the full service is not only the oil change, but many other service steps (air filter, spark plugs, checks, ...). So don't mark the service as done and "forget" all the other steps.



That's it. Your auto is now ready for another thousands of miles. The change interval ranges widely from 3000 to 20000 miles (5000 - 30000 km) and largely depends on the cars make and model and the oil used. Consult your cars manual and the packaging that came with your oil to determine its proper use. However, "long life" intervals above ~10000 miles (~15000 km) are usually not recommended for cars often used in short ranges.