Car Mechanics (UK)
DRAINING THE OIL
1 An engine flush added to the engine oil prior to draining can help to remove carbon deposits. Usually, the engine needs to be run for a few minutes after adding the flush and before draining the oil. Warm oil is easier to drain than cold because it’s thinner, so running the engine before adding the flush will also help.
2 Try to position the vehicle on level ground prior to draining the engine oil. Make sure it is secure, with one or more of the road wheels chocked and the handbrake on. Remove any undertrays that restrict access to the sump drain plug and/or oil filter.
3 Before draining the oil, ensure you know where the sump drain plug and oil filter are and that you have the right tools to remove them. First, try to undo the sump drain plug. You may need to slacken it with a breaker bar or long ratchet.
4 Position a drain tray or similar container underneath the drain plug. Release the oil filler cap to aid airflow through the engine and help drain the oil. Wearing gloves, carefully unscrew the drain plug and be prepared for a surge of oil once it has been released. Some drain plugs have a drain hole to avoid this type of messy surge (inset pic).
5 While the oil is draining from the engine, remove the oil filter. For spin-on filters use a filter wrench or cup to release it. Oil will leak out of the filter when it’s released, so wipe it up. Check that no seals remain attached to the oil filter housing.
6 Before fitting a new filter, add a smear of fresh oil to the seal around its screw thread. This will reduce the risk of the rubber seal catching and tearing when fitting the filter. Fit and tighten it by hand – DO NOT use the filter wrench or a cup to tighten it.
7 Where an oil filter is contained inside a canister or housing, use a suitable socket, extension bar and ratchet to undo its housing, then unscrew it by hand. Once removed, extract the old filter and renew the rubber seal that’s fitted around the thread of the canister – prise off the old one with a small screwdriver and fit the new one by hand.
8 Fit the new filter into the canister the same way up as the old one, noting that some need to be clicked into position. Refit the canister by hand, then finish it off with a torque wrench, tightening it to the recommended amount stated in your workshop manual or on the body of the housing (usually 25Nm).
9 Refit the sump plug. If a copper washer was fitted, renew it as it will have been crushed previously. Some sump plugs must be renewed with every oil service – they don’t cost that much anyway. Tighten it to the recommended torque setting and wipe around it to ensure it’s clean – this helps with checking for leaks once the engine is started.