Rarely do Atomic-4 engines wear out; they just corrode away.
The condition of the A4 before the trip is definitely the key of how
well it will be at the end of the trip.

Go to www.moyermarine.com and get Don Moyer's (worlds A4 guru)
"Maintenance and Repair Manual". The ~$50 cost will be the best
investment you can make in an A4. Most 'mechanics' nowadays no longer
'know' this engine. You can use the manual yourself and learn the 'ins
& outs' of the engine; or, 'loan' it to your mechanic when he works on
it - either way will result in heightened savings and prolonged life of
the engine.

Hope this helps