I just had my 89 accord dx (carb) auto trans 132k miles tuned up. It cost me 300.00 for a full tune up and oil change. They told me my distributor needs to be replaced because it was leaking past the “O” ring and had filled the distributor with oil. I asked about replacing the “O” ring and they said no, needs a new distributor and the total cost would be 400.00 to replace. Now I can get a rebuilt for about 100.00 and replace it myself, but why wouldn’t an “O” ring solve the problem? The repair shop came highly recommend, but are they truthful on this?

Thanks

To me, it sounds like you should fix or install a new distributor yourself. There's nothing special about that "O" ring.