Oil for Marine Power Engine

[jjackkrash]

I have a new-to-me 2000 Am. Skier Volante with the 5.7l Marine Power GM Vortec.  650 hours.  I am pretty sure the book recommends straight 30w for operating below 70 degrees f and 40w for above 70 degrees f, but I didn't get the manuals with it.  I regularly operate in temps that vary from 45-90 degrees.  

I would like to run Royal Purple Synthetic in either 15w-40 or 20w-50 marine/diesel grade oil.  Are there any other recommendations or anyone see any problems with this?  I don't really want to have to change oils frequently based on fluctuating air temperatures.

Thanks,

Jack

[Mike Harry]

Shouldnt have any problem running Royal Purple. Im off a fresh rebuild and thats what I am running. Now I will leave the viscosity question to someone with more knowledge than me. It never gets below 70 degrees here so I run 30 all the time.

You can actually call Royal Purple and they will give you a recommendation, thats what I did. And it worked out nice for me because they still use zddp and my girl is a little older

[jjackkrash]

Thanks, Mike, I have an e-mail into Royal Purple but the techs won't be there until after the weekend, so i guess I'll wait on the change.  I just found a manual online and it says 20w-40 or 20w-50 is ok, but I don't see why 15w-40 wouldn't work just as well.  That's what they recommend for Nautiques/PCM 5.7l. 

[phil]

I use Valvoline VR1 which is formulated with a lot of zinc. It's especially made for flat tappet cams. Perhaps I would run something different if it was a fresh rebuild but probably not. In my Moomba which has a GM 350, roller cam, I run Amsoil Marine 15-40.  I think the important things are that you run the correct winter/weight.

[jjackkrash]

From the Royal Purple Guys:

I would recommend Royal Purple SAE 10W-40 (part #01140, quart bottle) for year round use in your area.  It will offer enough viscosity once the engine is warm, but will have better flow than a straight 30 when the temperatures are cooler.  You can use our 15W-40, and the 20W-50 will work, but I wouldn't recommend it (too viscous).  The possibilities, in order of preference:

- Royal Purple SAE 10W-40 (part #01140, quart bottle)
- Royal Purple SAE 15W-40 (part #01154, quart bottle)
- Royal Purple SAE 20W-50 (part #01250, quart bottle)


Thanks for choosing Royal Purple and have a great day!


Best Regards,

Christopher Barker
Technical Services
Royal Purple, Inc.

*******

I think I am going to run the 15w-40 because its closer to the 20w-40 recommended in the book. 

[Mike Harry]

I have run royal purple in everything since I was 14 when I started racing karts.  Good stuff, ill vouch for them any day.

Plus the still use high amounts of zddp which is good for us guys with older engines.

[Midskier]

Jack, welcome aboard

and no worries on the oil you use
the engines run much cooler than in an automotive application
and most owners tend to change their oil @ regular intervals

10w30 , 10w40 are easier to find almost anywhere and will not be an issue on your engine
20w50 I would think is just too heavy unless you have A LOT of hours on your engine............ which @ 650 you don't
 
2000 volante is great a boat!

Dan T

[jjackkrash]

Thanks, Dan, Phil, and Mike!  

The online MP manuel said 20w-40 or 20W-50 was acceptable, but everyone I have talked to has said that 20w-50 was too heavy.  I am going to try 15w-40 the first go because that's what I have bought, and probably switch to 10W-40 the next change.  I appreciate the input.

Jack