Who knows what he did with the oil, he could tell you anything and how could you check on it.
If the oil has been sitting for 1 1/2 years, there could be a lot of condensation in it, plus you said it was dirty. It should not be dirty if it just sat.
Go and buy a good full syntech oil (5W-30) and change it A.S.A.P. If it gets dirty real fast (less than 1,000 miles) change it again. This guy could have had the same oil in there forever and not cared because the car seems to need some extra TLC.
A high quality oil should flush out the gunk within a couple of oil changes. Also a good long highway run (3-4 hours) should get things moving. Check it right after this to see if any more oil is coming out the passages.
