I would strongly recommend against trying to start an engine that has been sitting that long without taking some precautions first. With an engine that has been sitting that long, all the oil drips off of the cylinder walls and this can actually cause the engine to seize up with the piston rings and pistons becoming stuck to the cylinder walls. If you're fortunate and that hasn't happened, at very least the cylinder walls will be devoid of any oil and when you try to start the engine, the piston rings will be moving up and down in each cylinder with absolutely no lubrication, at least initially. This can cause massively accelerated engine wear and even break the piston rings.
To avoid this from happening, take each spark plug out and spray a light duty lubricant for about 2-3 seconds down into the spark plug hole to provide lubrication to the piston rings, pistons and cylinder walls. Let the engine sit for days so the lubricant can work its way between the metal parts. A good lubricant for this is WD-40 and comes with a straw taped to the side of the can that you can connect to the spray nozzle so you can reach further down into the spark plug holes in the cylinder head and combustion chambers.
After you have done this, there can be a little bit of WD-40 inside each combustion chamber and this can cause a hydro-lock situation, where the piston tries to compress the WD-40, (fluids can't be compressed), when it comes up in the cylinder and since the fluid can't be compressed, it can cause serious engine damage because the piston can't come up any further into the cylinder without a connecting rod becoming bent, or worse. To avoid this from happening, before you try to start/turn over the engine, leave the spark plugs out/removed and disconnect the coil wire that plugs into the middle of the distributor cap. This will prevent any spark from getting to the spark plugs and possibly igniting fuel vapor and starting a fire. Next, turn the key to start to see if the engine is free and able to rotate. If it can, turn the engine over for about 10 seconds or so and this will clear out any remaining liquid WD-40 out of each cylinder and avoid hydro-lock caused engine damage.
After you're done with that, then you can re-install the spark plugs and coil wire, then try to get the engine started. Keep in mind the WD-40 that was sprayed into the cylinders will get past the piston rings and down into the crankcase and mix with the oil inside the engine. If its brand new oil, this will contaminate and dilute the oil, reducing its protection capabilities. So as long as there's oil in the engine now, it might be best to not change it until the engine has been running for a few minutes. This will also give the oil a chance to get hot and will drain out of the engine much easier and more thoroughly than if it was cold.
Be aware that with a vehicle that has been sitting that long, it is possible that the gaskets and seals all throughout the drivetrain have dried out, cracked and will leak, including the engine, transmission and rear axle.
Also, if the battery is 20 years old, it is absolutely shot and dead as a door nail. It is likely it wont start the car even with a jump start or a battery charger hooked up to it. The spark plug wires will also be very dry rotted and need replacing. The shock absorbers will also need replacing as the rubber mounts will be totally dry rotted and will fall apart after sitting for 20 years. Thankfully, shock absorbers don't cost very much compared to MacPherson struts. The tires will also be dry rotted and need replacing.
To get the engine to fire up and run, you'll need to spray some starer fluid down the carburetor. You may have to do this many times before the engine will start and run. A fresh set of spark plugs will help a lot.
For a 1975 vintage Corolla, a 10W-30 viscosity will be fine. If you're interested, I can get provide you with quality Wix filters at wholesale prices for the oil filter, air filter, fuel filter and automatic transmission filter. To give you an example, the wholesale price for a high quality Wix oil filter for this car equipped with the 1.6 litre engine is only $5.50. I can also get you wholesale prices for NGK spark plugs/wire sets and Trico wiper blades as well. Private message me if you're interested.
Here is a link to my companies online Product Application Guide that will provide you with the part numbers for all the various filters for your Corolla -
http://www.amsoil.com/AmsoilLookups/VintageFilterLookup.aspx?zo=349698
I hope this has been of help. How many miles are on this car?
