Is oil still good after not much use?

Answer 1

No. Not in the way you mean.
Oil is a mixture of other chemicals.
Over a LONG TIME the additives will dissipate, rendering the Oil less effective.
"synthetic oil intervals between oil changes can be much, much longer: "In some cases as much as 15,000 miles or one year."
"Some mechanics, say you should change your oil every 5,000 miles with synthetic oil."

Answer 2

Oil will always be good, but after a little use it will hold a few particles After a long time, even with little use, in the engine it will pick up a number of chemicals