CHANGING ENGINE OIL
While oil chemistry is immensely complex, changing the oil is one of the most important and Diy-friendly exercises that you can undertake and is a good place for a novice to start. Regular oil changes are good for engines and many technicians view many official oil change intervals as being excessively long. Every 10,000 miles or 12 months, whichever comes first, tends to be a general recommendation unless your car-marker stipulates a shorter frequency.
Before starting work, research the quantity and specification of the oil required. Buy a good quality oil filter and replacement sump drain seal.
One of the trickiest tasks on modern cars is removing the plastic undertray that protects the sump. Some cars offer more accessible drain plugs (see inset).
Opinions differ on whether, or not, an engine flush solution should be used. If you would like to use one, follow the instructions on the bottle.
You may have to raise the car in order to access the underside. Using drive-on ramps, or jacking-up the car and supporting it on axle stands are the safest options.
If the engine is cold, take the car for a short drive. A run of a few miles will heat the oil so that it can flow out more easily.
The oil flow can increase suddenly as the plug is removed. Direct the flow into a suitable receptacle – bespoke drain pans are designed for this purpose.
Undo, or remove, the oil filler cap to help the old oil flow out more easily. Wearing protective gloves, turn the sump nut anti-clockwise, but be aware that oil can start to drip as soon as the plug is loosened.
Be prepared to catch any oil that may flow from the filter as it is removed. These metal-bodied filters can be deposited for recycling at many household tips.
Choose an appropriate spin-on oil filter removal tool. Hammering a screwdriver through the filter body to turn it is a messy and risky alternative.
Spin-on oil filters can be rather stubborn to remove, especially if they have been overtightened at the last service.
As the oil flow reduces to a trickle, unscrew the engine oil filter. The plastic, or aluminium, top on cartridge-type oil filters should unscrew easily.
While not applying throttle, start the engine and allow it to idle for several minutes – the oil pressure warning light must extinguish promptly. Stop the engine and leave it for several minutes so the oil level can stabilise. Wipe and dip the stick again and note the reading.
Check both the sump plug and oil filter to engine mating points for oil leaks. If oil stains/mists/ drops are evident, they indicate that leaking seals might be responsible.
Refit the undertray and dispose of the used oil at a household recycling centre. Reset the service indicator.
Never add oil over and above the quantity stated in the car specifications – overfilling can damage the engine and be dangerous.
If you could not carry out Step 15, you may notice a difference in readings between those taken in Steps 19 and 21, due to the filter being filled with oil.