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ANGUS
07-17-2007, 03:51 PM
I have a 454/330 with 300 hours on it....why not run a multi-vis 15w40 rather than the straight 30 weight called for by the factory? Any comments would be appreciated .....seems to me it makes much more sense offering improved startup protection as well as cruising protection.I am all ears!

blackhawk
07-17-2007, 05:19 PM
IMO it wouldn't hurt to use either. I personally would like to see one of the viscosity numbers higher, like 25w40 or 15w50, but that is personal preference. I have used 25w40, 20w50, SAE30 and SAE40 in my boats.

But FYI the first number in a multi-viscosity oil is for COLD climates. I believe that number is a 0*F viscosity number. So "cold" start up isn't an issue like an auto would be at -15* and SAE 40 in the pan!

Many people recommend single viscosity oils in boats because they don't have polymers that can break down. And boating climates usually don't get that cold.

Like I said in the other thread, ask 10 people about motor oil and you'll get 10 different answers. The biggest issue with motor oil is not changing it often enough.

Squiggy111
07-18-2007, 12:28 AM
I just rebuilt the 454/330hp in my Carver , it's a counte rotating motor & was advised by the enginering shop that did my work to use a straight 40wt......with a special high zinc content.....

CHACHI
07-23-2007, 06:19 AM
Many people recommend single viscosity oils in boats because they don't have polymers that can break down.
That depends on the type of the polymer the oil manufacturer uses.
A multi-vis 25w40 will maintain a greater percentage of its 210*F viscosity than a straight 40 at temps over 210*F because of the polymer. Multi-vis oils thin less than straight weights.
Ken

BUIZILLA
07-23-2007, 07:29 AM
Multi-vis oils thin less than straight weights. Ken that's some good advice you can take straight to the bank... :yes: :yes:

JH