""""IF"""" you have an oil filter and the adapter is the large variety, use a WIX 51515R Obtainable from any NAPA parts house. WIX makes all the filters for NAPA and if by chance they have a NAPA brand, it's a 1515R. Most VW engines do not have a filter unless the previous owner or engine builder machined it for a full flow system or,,, someone installed an oil pump with an oil filter adapter. If that's the case, remove the filter and take it to your auto parts store so they can match it up. If it's been sitting for 3 years then along with an oil change, do a valve adjustment, replace the fuel filters and drain any fuel in the tank and carb's. Re-fill with fresh gasoline. (Today's oil, thanks to the EPA is crap, so make a decision based on this: http://forums.pelicanparts.com/showthread.php?t=367300&highlight=oil
Usually 20-50 for summer and a lighte oil if it gets real cold in your area.
While you're in the engine compartment, you may as well do a complete tune up, point/condenser if you have them, new distributor cap, new rotor, new spark plugs and also check your spark plug wires.
Depending on your area, you may want to check for rodent damage such as chewed wires etc. It's quite common in some area's of the country.
Check your air cleaners and if you have K&N's then clean them and re-oil. If you have paper filters then replace them. Drain the transaxle fluid and re-fill with 1 gallon of fresh oil (probably 80-90 weight) Obviously you'll probably need to install a new battery as I wouldn't trust a battery that's been sitting that long. Check your tires. If they have started to rot then replace them (regardless of tread depth, tires are only good for 5 years and after that, they can blow out) and, don't forget to check your brake system. Probably you should flush the brake fluid and re-fill with fresh fluid. (THis can be done rather easily and you won't need to bleed the system if you install a 1/8" hose over the bleeder valve and insert the hose into a quart size container containing about 1 inch of fresh fluid. Crack open the bleeder valve and pump the brakes making sure the reservoir stays full. This should be done backwards from bleeding in that you'll start at the closest wheel to the reservoir then progressively go to the furthest. By having the tube in fluid, you won't suck up any air. Pump at least 4 to 5 times then close off that bleeder and move to the next)