The engine oil level should be checked often to make sure the engine has enough oil for safe operation. The oil should also be checked for condition to help determine if it should be changed. Check this whenever you open the bonnet.

Before checking the oil level, the engine has to be turned off. The oil must be given a few minutes to run off engine parts and collect back into the oil pan. If you check the oil level just after shutdown, you could get an inaccurate oil level reading.

WARNING: Do not attempt to check oil level with the engine running. Engine oil splash inside the oil pan will give an inaccurate reading.

CAUTION: The oil and dipstick from an engine that has just been shut off will be hot and can cause burns. Avoid dripping oil from the dipstick on hot engine parts because oil can be flammable.

Oil on the dipstick can be used to determine engine condition. The longer the engine oil stays in the engine, the more contaminated it gets. Heat and contaminants such as moisture and dirt eventually cause the oil to lose some of its protective qualities. You can get a rough idea of the condition of the oil by observing its color on the dipstick. New oil and oil that has not been contaminated has a clear, light brown color. Oil that has been in the engine a long time turns black and has a dirty appearance. When you see dirty oil, determine when it was last changed. If it was more than three months before, it's probably time for an oil change.

CUSTOMER CARE: Checking oil level and oil condition can save car owners many dollars in expensive repairs down the road. A good technician will be alert to engine oil problems and will consult regularly with customers about the best way to avoid costly problems.

After reading, push the dipstick back into position. Make sure it is firmly seated so no water or dirt can enter the engine. Check that no tools or rags have been left in the engine compartment.

Change Engine Oil and Oil Filter

Changing the engine oil regularly is the most important thing that can be done for long engine life. The more frequently oil is changed, the longer the engine can go before it needs an overhaul. Oil begins to deteriorate as soon as it goes into service. Hot oil inside the engine oxidizes or combines with oxygen. Oxidation breaks the oil down chemically. Water, a byproduct of the combustion inside the cylinders, can enter the oil. The water reacts with sulfur, which is a chemical in the oil. The water and sulfur can combine to form sulfuric acid. The acid can attack and damage bearings and other engine parts.

Engine oil also gets contaminated over time. Dirt, dust, and water can get into the oil. Dirt and dust often contain abrasive particles that can damage engine parts. Water that gets in the oil causes sludge. Sludge is a mud-like mixture of oil and water that can plug oil passages inside the engine. .

Oil change recommendations are based upon a time/mileage interval. With my Morgans,  I prefer this to be 2000 miles or 2 months. Oil change intervals should also consider car operating conditions. During cold or wet weather, oil should be changed more frequently, because short trips and stop-and-start driving are harder on oil than long trips and highway driving. Oil should also be changed more frequently if the automobile is driven in areas where there is a lot of dirt and dust in the air. Acid formation is possible in engines that are rarely driven. A car that is stored for the winter should have the oil changed more
regularly than the mileage interval specified by the manufacturer.

WARNING: Oil should be changed hot, which means as soon as possible after the car has been driven at operating temperature. If the car is parked for a long period before oil is changed, it allows the oil to cool and gives particles of dirt and water time to stick to parts of the engine. When the oil is drained, the dirt and water stay in the engine.

CAUTION: Always wear eye protection when changing oil. Hot oil could splash into the eyes.

The first step in the oil change procedure is to safely raise the car on a hoist or on jack safety stands. Set the safety brake and put the transmission in gear. Then place an oil drain pan under the drain plug before you begin to drain the oil. Use an oil drain pan that will hold five or six quarts. Do not mix up the transmission drain plug, which is located in the bottom of the transmission, and the oil drain plug. 

When the plug is located, place the correct size open-end wrench snugly on the drain plug. Have the pan ready.Turn the drain plug counter-clockwise to loosen. Pull it out quickly, allowing the oil to drain into the pan. Be careful, because the oil is hot. Allow the oil time to drain.

The drain plug should be cleaned and inspected for wear in the thread area. Replacement drain plugs are available that are slightly oversize with self-taping threads. If you find a drain plug that has cross threads or will not tighten properly, you will have to install an oversize drain plug. These come with a gasket to help them seal any leaks.

Original equipment drain plugs have a sealing washer that fits on the drain plug. The sealing washer is made of soft metal, such as copper or brass, and may even have a sealant applied to its surface. The purpose of the washer is to prevent leaks around the drain plug. Always install a new sealing washer.

Replace the drain plug, turning it clockwise by hand. Look up the specifications for the drain plug torque in the shop service manual. Use a torque wrench to tighten the drain plug. Over-tightening will lead to leakage and stripped threads.

WARNING: The use of large adjustable wrenches for tightening drain plugs is a common reason for stripped drain plug threads. The best tool to use is a torque wrench.

The oil filter must be changed each time the oil is changed. Most oil filters are accessible under the engine. Locate the oil filter on the side of the block. The oil filter is ideally changed while the car is up on the hoist or supported by jack safety stands. Put a drain pan under the filter to catch the oil that comes out.

To remove an oil filter, grip the outside of the filter housing. The constant heating and cooling of the filter can make it very tight and difficult to remove. A variety of tools are available to grip and turn an oil filter. Most are adjustable to fit different diameters of oil filters.

Put the oil filter tool around the filter cartridge. Turn it counterclockwise with the tool until it can be turned by hand. Set the filter in the drain pan to drain and then dispose of it properly.

Use a clean rag to wipe the mounting surface on the engine where the filter fits. Put a light coat of grease or oil on the rubber gasket of the new filter. Screw the filter on by turning it clockwise. Tighten it snugly by hand. Do not use the tool to tighten it.

SERVICE TIP: If the filter mounting allows, fill the filter with the correct type of engine oil before installing it on the engine. This will reduce the period of time required to fill the filter and get oil to the engine on start up. This can prevent engine wear. Filling the filter is especially important on cars with turbochargers. The turbocharger bearings are subject to oil starvation problems if the oil does not get to them quickly.

The car can now be lowered to the ground. Raise the hood and locate the oil filler cap. The cap is usually found on one of the valve covers. Remove the oil filter cap. Look up the amount of oil to refill the engine under the "Capacity" section of the owner's manual. Install a clean funnel in the oil fill hole to prevent spilling oil on the engine. Open a container of oil and pour it into the engine until the recommended amount has been added.. Check the oil level with the dipstick as described earlier. Replace the filler cap. Check the drain plug for leaks.

After the oil change is completed and the required amount of oil is added, start up the engine. Watch under the engine for leaks. An oil filter leak will typically cause large amounts of oil to pour out. If the filter leaks, shut the engine off quickly. Either the filter is not tight enough or the filter gasket is defective. If the filter is not found to be loose, install a new filter and the correct amount of oil again. If there are no leaks, allow the engine to warm up to operating temperature. Continue to check for leaks at the filter or drain plugs. Make a final check of the oil level. When oil is pumped into the new filter to fill it the oil level will drop. You may need to add more oil.

Clean any oil spilled on the engine. Check under the hood for rags and tools. Then shut the hood.

WARNING: Used engine oil and the used oil in an old filter must be disposed of properly. Oil thrown in the trash can end up in a landfill where it can seep into our groundwater. Dispose of the used oil and oil filter correctly so that they do not end up harming the environment. The oil should be taken to a recycler. The oil filter should be completely drained and then crushed.