My mehanic claims that synthetics are very high detergent and are bad
to start using on old engines. My 87 Accord has 188,000 miles. He
said if it had had synthetic in it regularly before 100,000 miles it
would be fine. He reccommends using some of that seal swelling high
mileage stuff, but I'm hesitant to use anything that would soften the
old seals. Also he says the Honda oil filters are probably a waste of
money. He says he's not sure, but he knows the US aotomakers charge
too much for their filters. Don't filters need to have ratings like
engine oils.