Oil change 1991 g60 1.8L

Changing the oil in my son's g60- 91 1.8L supercharged- no
specifications on the car for oil specs. Local VW dealer says bring
it in for a $40 oil change

Local shops have recommemded everything from 5W20 to 20W50- I'd
think a heavier oil would be best but what's RIGHT? Also
recommendations for a filter appreciated- so long as it isn't an
orange one.

Jeff