When you say burn off excess oil are you meaning it's overfilled ? If so, if it's overfilled considerably I would recommend draining some as this can also cause seals to blow :( If you try some injector cleaner in it, it wouldn't hurt to give it a good run, with the fact that it is not being driven a lot it may even be beneficial to chuck in an engine oil treatment something like Nulon or similar to help with lubrication. At least you know the history of the car so unless the nephew has really flogged it hopefully it should be OK
