2006 Nautique PCM 350 CU / 330 HP - Dino Vs Synthetic Oil

[Rusty Axle]

Looking through the service manual for this motor, PCM recommends sticking with dino oil vs. synthetic.

Synthetic oil has a host of superior specs vs. dino oil, especially shear resistance (oil film giving way between two mechanical surfaces).

My understanding is that the engine is a GM small block, so synthetic would be commonly used when it is installed in automobiles.

I believe that PCM simply adds external components (impeller, marine grade alternator etc) and nothing is different internally. Same pistons, rings, bearings etc. Possibly a different spec camshaft, but that would have no impact on oil choice.

What possible harm could synthetic oil cause?

[srock]

In this scenerio, there is no harm in synthetic that meets spec except to the wallet.

[NautiqueJeff]

As long as you stick to the specs here, you should be good. Synthetic should be OK. Yours calls for 15W-40.

https://www.planetnautique.com/vb5/f...specifications

[Rusty Axle]

Thanks very much for the perspective.

My interest is in preserving the integrity of the motor internals for as long as possible.

I gather that neither of you use synthetic.

Which leads me to think that it may be reasonable to assume that since the oil is going to be changed every season regardless of hours on the motor, the benefits of synthetic may not be realized vs. the cost.