Changing your oil especially on a classic is an easy and satisfying job, as well as that regular oil changes will extend the life of your engine and increase the time between rebuilds.
Before you start, you'll need the following items to make the job easier:
1. New oil
2. An oil drain container
3. Lots of old rags
4. Socket set or drain plug spanner
5. An oil filter remover
6. A new copper washer
The first thing to do is to start your engine and run until it is fully warmed up to get some heat into the oil and if you an oil cooler with thermostat it will make sure it has opened and oil is flowing.
Leave the engine to stand for 5 or 10 minutes this will allow the oil to drain back to the sump and reduce the chances of burning yourself.
Removed the dipstick out or loosen it off and break the seal where it plugs into the engine dipstick tube to prevent a vacuum building up behind the oil when you start to drain it
Get your drain oil container and place it under the sump drain plug. The combined drainer / container types are best but if you lay them on their side, there's a pop-out plug. When you drain the oil, it runs into the side of the container, then you can put the plug back in and use the same container to take the oil away.
Put your rubber gloves on as oil especially oil oil can cause skin cancer.
Use your socket set or plug spanner to loosen the sump plug just slightly as once it is loose it can usually be removed by hand. On my MGB there is not enough room to get a socket set in with the oil drainer in place so I have to slacken the drain plug then put the container in place (what I would give for a 4 post ramp!!!!). Once it's loose, remove it by hand and let the oil drain into the container.
I have fitted a magnetic plug on the MGB and as can be seen in the picture it collects a lot of metal particles which would be floating round the engine causing damage. You can get strong magnets which go round the oil filter to keep all these particles in the filter although I have not tried them
Remove the old copper washer from the sump plug and throw it away. Replace it with a new one they are very cheap 25 pence for an MGB and they stop one source of leaks.
At this point I usually pour some new oil in to help flush out some of the last of the old oil (you can never get all the old oil out especially if you have an oil cooler). Once the oil coming out of the drain hole is reasonably clear I stop putting the oil in.
Use some of the oil from the drain container on the end of a rag to wipe around the drain hole in the sump. This will help clean any mess away and leave you with a smooth surface. Screw the sump plug back in by hand until it's finger tight and then use your socket set to crush the washer. This can vary from a quarter turn to a half turn. Don't overdo it or you'll strip the threads. Similarly, don't leave it too loose or it will fall out. If in doubt, use a torque wrench set to the value indicated in the workshop shop manual.
It is now time to remove you old oil filter so get your oil filter remover out. There are many different types available from chain wrenches to a large socket set type, K&N have started to produce a filter with a 1" nut welded to it so it can be taken off with a spanner.
Push the oil drain container under the oil filter - when you spin it off, there will be a lot of oil comes out. Use the filter remover of choice to grip the oil filter and spin it off anticlockwise. This is why a filter remover is a must-have. Stabbing the filter with a screwdriver and using brute force may work, but you will have oil everywhere, nasty sharp bit protruding from your oil filter and also you do not know what is inside the filter with respect to the engine and you could damaged this.
Clean off the face of the oil filter mount on the side of the engine block using a clean rag and use a little oil on a rag to wipe around the seal of the new filter and spin it on by hand. Once it's locked against the filter mounting another quarter-turn by hand is normally enough to secure it in place do not use your oil filter remover to tighten the filter.
Pull the container out from under the car and use a rag to wipe down any excess oil that has spilled down the side of the engine block. Pay attention around the sump plug and the filter. These are places you'll be checking later for leaks so the cleaner they are now, the better.
Use a little WD40 on the oil container and an old rag to clean the remaining oil down into the container. Put the plug back in and make sure it fits snug. That's your waste oil take it to your local authority waste transfer station.
Put the dipstick back in and removed the oil filler cap.
Fill the engine with fresh oil nice and slowly so you don't get air locks and keep checking the dipstick to ensure you get the level right on the stick.
Pull the main high tension wire from the distributor cap or in some way disable the engine so that you can crank it over but it WILL NOT start. Crank it over until the low pressure light goes off, and another 15-20 seconds for good measure. You are pumping new oil into the empty filter and then expelling all the air from the oil lines and cavities.
Replace the high tension lead and start the engine and let it idle for a minute or so. Stop the engine. You don't want you crawling under a car to look for leaks when the engine is running. Have a look at the side of the engine block around the oil filter. Check the area around the sump drain too. Both should be as clean as you left them with no sign of leaks. If there's a leak, a little tightening of the drain plug or filter should cure it.