Oil

I haven't changed the oil in my '88 Grand Caravan in over 14 years. That has nothing to do with an oil leak accept that seal conditioners and other additives wear out in about 3,000 miles. I do add one quart every 1,000 miles, and that is enough to replenish the additives.

Obviously 14 years is abuse, not neglect, but the point is your leak has nothing to do with an ignored oil change. Changing the oil now isn't going to magically fix a leak. You need to have the location of the leak diagnosed to determine the proper course of action.