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Oil brand and type

Straight 30wt in 5 gallon pails. Walmart has it in gallon jugs. Marine engines are more like industrial than transport engines. A heavy-duty lube like the 30wt is recommended by most marine manufacturers.
Multi vis oils are overkill for marine engines since they typically do not operate in below-freezing conditions.
 
.."Multi vis oils are overkill for marine engines since they typically do not operate in below-freezing conditions"

That has nothing to do with it! Every time a cold motor starts up the bearings take a beating until the oil pressure comes up. Using a 10W30 (for example) oil lessens that beating.

Multi vis oils are a modern miracle of lubrication engineering. Why on earth would anyone still use straight weight oil from the 1930s?

Jeff
 
The only reason to use multi vis is to cover wide temperature conditions. The "W" is for "winter", not "weight". Your 10W-30 still behaves just like straight SAE30 in warm weather.
 
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Per a conversation I has with Andy Granatelli ( I bought an engine from him once).... multi weights for hydraulic liftered engines... "straight" for mechanicals...
 
I had twin 1982 Merc 5.0. Manual called for marine 30w. Multi weight only if no straight weight was available. Upgrade to 5.7's last year. 5.0 were still kicking. I use Pennzoil and sometimes West Marine brand when on sale for $20.
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.."The only reason to use multi vis is to cover wide temperature conditions. "

I believe I already covered that inaccuracy. Every time a motor fires up--with still no oil pressure--it needs a thinner oil to get things going.

Jeff
 
All I will say is use what ever you want as long as it meets Manufactures specifications.

If in doubt, use their oil only and you wont have to ask this type of question.

Mercs spec for almost all engines is 25w-40w standard non synthetic oil and a "tiny" oil filter.



Yet they use synthetic gear oil now............go figure.
 
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