Complete rebuild/teardown on outboard motors every 5 years.

[Foxsea]

i would be more reliant on the oil sample to well me if there was particulate of salt water in the oil

Unfortunately, for a few bucks, you get what you paid for - not much. On heavy equipment, we sent samples in to get a baseline (Finning), then monitored changes over time. This helped determine the internal state and when an overhaul made sense. Oil changes are expensive. Sampling would indicate when needed. Some engines ran 14,000 hours before major work. None of this is relevant with outboards.

 

[Foxsea]

Does Your Yamaha Outboard Head Gasket Need to be Repaired? - PartsVu Xchange

When does your Yamaha outboard head gasket need to be replaced? This article discussed top signs that your head gasket needs replacement.

www.partsvu.com

So no symptoms = no need. Idles good, runs good, it's good. Maybe Yamaha had a bad batch of head gaskets installed so needed to publish this.

 

[noluck]

Unfortunately, for a few bucks, you get what you paid for - not much. On heavy equipment, we sent samples in to get a baseline (Finning), then monitored changes over time. This helped determine the internal state and when an overhaul made sense. Oil changes are expensive. Sampling would indicate when needed. Some engines ran 14,000 hours before major work. None of this is relevant with outboards.

you will see higher traces of sodium if you start burning saltwater

 

[scott craven]

you will see higher traces of sodium if you start burning saltwater

I'm thinking your motor wouldn't last long in that situation....

 

[ship happens]

If a head gasket was in fact leaking a bit of water into the cylinder, there would be a really clean spot or area on the piston. The spark plug will show signs of that as well in most cases. Typically on a 4stroke outboard, if that is in fact happening you will have actual engine running symptoms and or it will be noticeable in the engine oil itself.

I'm on team change don't do an oil sample and stick to changing engine fluids on time.

 

[profisher]

Head gasket failure is just as much about water leaking into the cylinder...becoming super heated steam and melting an aluminum piston. It can happen quite quickly. If you ever overheat your engine badly by way of a plugged water inlet or faulty water pump...that is the time to really be sure the head gaskets weren't damaged or that you warped a head. Salt build up in the head water passages can also eat away at mated surfaces and the gaskets.