Delo 5w/40 or 15/40 oil?

Duane in Indy wrote: I would sooner think that the thickness of the lake ice would have more of a bearing on if you needed 5W oil.

Yeah exactly I don’t need 5W it’s just all they had on the shelf.

Crmaverick wrote: KENO wrote: Crmaverick wrote: The motor is a PCM 454 HO with a roller cam so I don’t need to worry about a high zinc oil. You might want to verify that it's a roller cam. It's not what it was made with in 84. You think it’s been changed out? I wonder how I could verify that without pulling it apart

They didn't have roller cams in production Chevy marine engines in 84

I'd just assume it's a regular ol' flat tappet hydraulic cam and choose my oil accordingly.

You could pull the intake to verify what you have for sure

KENO wrote: Crmaverick wrote: The motor is a PCM 454 HO with a roller cam so I don’t need to worry about a high zinc oil. You might want to verify that it's a roller cam. It's not what it was made with in 84.

You think it’s been changed out? I wonder how I could verify that without pulling it apart

You would need to be well below freezing -- almost to zero degrees to worry about 5W vs 15W. I run Valvoline VR1 synthetic 20W 50 in my rig.

JQ

The dreaded "which oil" question. Ask 10 people and get 15 answers.

The "w" in motor oil stands for winter. The first number in the oil classification refers to a cold-weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures. For example, a 5W- motor oil will flow better at lower temperatures than a 15W- motor oil. The higher number, following the “w” refers to hot weather viscosity, or how fluid your oil is at hot temperatures. The higher the number, the thicker the oil at a specified temperature.

If you plan on operating the boat in very cold temperatures, then stay with a 5W winter weight. If you (like most of us) only run in the warmer months, then a 15W should be fine.

Now...for the question you didn't ask: should you run a higher weight like a 15W 50 or 20W 50? In some circumstances, thicker oil can be used to compensate for increased bearing clearances (gaps between bearing and rotating shaft) that have developed over the years. A large change in bearing clearances can result in poorer lubrication. Be sure that you follow the recommendations for motor oil viscosity in the engine owner's manual.

One more thing...high zinc (ZDDP) oil will work just fine in your engine. That assumes that you don't have a catalytic converter.    

JQ

Thanks to the Valvoline website