Help with 1986 90hp Mercury inline 6

" I recently purchased a boat

" I recently purchased a boat with a 1986 Mercury 90 hp in-line 6. I'm not sure of the service history of the motor but it starts and runs pretty smooth. Was this a good merc motor in its day? And how well do they hold up. I'm a little afraid of relying on an older motor. I did a compression test on the 6 cylinders and they all read around 140 lbs. There also seems to be good spark on all leads. I drained the lower unit oil and it was jet black and smelled awful, not much metal showed though. I hope this isn't a bad sign of an early death. I have changed the spark plugs but what other parts should I replace or service before spring launch? I'd like to do the installations myself but Ive only done minor work on outboards, so let me know if I should leave this to a pro. Thanks for your help.

Charlie "

" Replace the impeller,replace

" Replace the impeller,replace the impeller!!. Many used boat buyers and used motors have come to grief because of cooling problems.Don't make that mistake. "

CHARLIE...This motor may be e

CHARLIE...This motor may be equipped with an autoblend unit. I highly reccomend if it has to remove it and mix the fuel 50 to 1 in the tank. These units (from my experiences) are not reliable and if not functioning correctly could cause serious damage to the motor without your knowledge...DJ