I have 780 hr on 496 mags never any problems,
and its in salt water 50% of the time.I ve seen
496 s down here in fort myers with over 3000 hrs
on them, the key to it in my mind is change them
oils, I change them every 30 to 35 hrs.

how to prevent catastrophic failures.......
maintenance maintenance maintenance,,,
clean oil clean oil clean oil.......
how its driven how its driven .........
and even then ......chit happens....
in my limited opinion..... the 496 is a good engine
there will be no shortage of parts in the coming yrs
and there are lots of blown 496 out there
no full throttle hole shots
and dont hold the engine at full throttle once the hard pulling is done
to get those last 2 /3 mph

i run pretty hard....... between 4500 and 5000 rpm about 50% of the time and certainly around 4000 rpm for 35% of the remaining 50% mine runs just fine...... but she gets a full service both in the spring and before winter
i change the oil every 20 to 25 hrs
the maintenance is almost as expensive as the fuel...........