How an engine’s oil filter works

Oil Filter Change Image

The oil filter catches contaminants such as tiny metal particles that could otherwise damage engine parts, including the oil pump, and should always be changed whenever the oil is renewed.

The engine oil can be drained via the sump plug (recommended) or through the dipstick hole with an oil extraction pump. Always use the correct filter and oil grade for your car’s engine and check the new oil is at the right level on the dipstick.

This is a relatively easy task and you’ll need only basic tools for the job - as well as an oil filter wrench. If you use the oil extraction technique this task can be completed within half an hour. Allow an hour if you want to empty the oil via the sump plug.

When should you change your engine oil and filter?

“Some high-performance models need to have their oil and filter changed every 6000 miles or six months”

This is one of the most debated subjects among DIY mechanics. Every engine is different and requires a specific grade of oil - always consult your car’s handbook or refer to Haynes for the correct type. Some high-performance models need to have their oil and filter changed every 6000 miles or six months (whichever comes sooner).

Other cars with long-life oil can go as far as 24,000 miles (or more). However, here at Haynes we recommend you change oil and filter once a year, or every 12,000 miles, whichever comes first, depending on your handbook’s advice.

Never be tempted to skip a filter change when you change the oil - the old filter will contaminate the new oil.

All cars are slightly different, so if it is time to change your oil and filter, find your car for specific instructions.

Warning

Never be tempted to skip a filter change - the old filter will contaminate the new oil

How to change your engine oil and filter via the sump

Here's an example of how it's done. FInd out how to do it on your model

In the adjacent video we show you how to change your vehicle's oil, or you can follow the step-by-step instructions down below.

  1. Frequent oil and filter changes are the most important preventative maintenance procedures which can be undertaken by the DIY owner. As engine oil ages, it becomes diluted and contaminated, which leads to premature engine wear.  
  2. Before starting this procedure, gather together all the necessary tools and materials. Also make sure that you have plenty of clean rags and newspapers handy, to mop-up any spills. Ideally, the engine oil should be warm, as it will drain more easily, and more built-up sludge will be removed with it. Take care not to touch the exhaust or any other hot parts of the engine when working under the car. To avoid any possibility of scalding, and to protect yourself from possible skin irritants and other harmful contaminants in used engine oils, it is advisable to wear gloves when carrying out this work.  
  3. Firmly apply the handbrake, chock the rear wheels then jack up the front of the car and support it on axle stands. Undo the fasteners and remove the engine undershield (where fitted). 
  4. Rotate the oil filler cap anti-clockwise and remove it.
  5. Using a spanner, or preferably a socket and bar, slacken the drain plug about half a turn. Position the draining container under the drain plug, then quickly remove the plug completely, and allow the oil to drain.
  6. Allow some time for the oil to drain, noting that it may be necessary to reposition the container as the oil flow slows to a trickle.  
  7. After all the oil has drained, wipe the drain plug with a clean rag. Examine the condition of the drain plug sealing ring, and renew it if it shows signs of flattening or other damage which may prevent an oil-tight seal (it is generally considered good practice to fit a new seal every time). Note that on some engines the seal is integral with the drain plug. Clean the area around the drain plug opening, and refit the plug complete with the seal and tighten it to the specified torque. On some engines, the seal is integral with the drain plug.
  8. Move the container into position under the oil filter.  
  9. Depending on the type of oil filter, use an oil filter removal tool to slacken it initially, then unscrew it by hand the rest of the way and remove it from beneath. Alternatively, unscrew it from within the engine bay and lift it out. Empty the oil from the old filter into the container.
  10. Use a clean rag to remove all oil, dirt and sludge from the filter sealing area on the engine.  
  11. Apply a light coating of clean engine oil to the sealing ring on the new filter, then screw the filter into position on the engine. Tighten the filter firmly by hand only – do not use any tools. Apply a light coating of engine oil to the sealing ring on the new filter.
  12. Remove the old oil and all tools from under the car, then lower the car to the ground.  
  13. Fill the engine through the filler hole, using the correct grade and type of oil. Pour in half the specified quantity of oil first, then wait a few minutes for the oil to drain into the sump. Continue to add oil, a small quantity at a time, until the level is up to the lower mark on the dipstick. Adding approximately a further 0.5 to 1.0 litre will bring the level up to the upper mark on the dipstick.  
  14. Start the engine and run it for a few minutes, while checking for leaks around the oil filter seal and the sump drain plug. Note that there may be a delay of a few seconds before the oil pressure warning light goes out when the engine is first started, as the oil circulates through the new oil filter and the engine oil galleries before the pressure builds-up.  
  15. Stop the engine and wait a few minutes for the oil to settle in the sump once more. With the new oil circulated and the filter now completely full, recheck the level on the dipstick, and add more oil as necessary.  
  16. Dispose of the used engine oil and filter safely. Do not discard the old filter with domestic household waste. The facility for waste oil disposal provided by many local council refuse tips and/or recycling centres generally has a filter receptacle alongside.

Tools you will need

Mainly basic tools are required for this job, although you’ll need a filter wrench, a torque wrench and a trolley jack.

  • Wheel chocks
  • Rubber gloves
  • Breaker bar
  • Socket set
  • Filter wrench
  • Screwdriver
  • Torque wrench
  • Trolley jack

How much does it cost to change engine oil and a filter?

 

Oil £5-£25 per litre
Filter £3-£30
Garage fee savings £50-£150

Every car is different, so before you view the full instructions, find yours…