Oil viscosity for 89 350 King Cobra

[Donzi GT250]

I have a 1989 OMC 350 King Cobra engine 270 HP 350APRMED and the manual indicates SAE30 engine oil. But many of my friends and a couple mechanics say to use SAE40 weight engine oil instead of the SAE30 weight. I live in northern Ohio and it can get well into the 90's in the summer here, but the spring and falls are cool.

BTW I did a search on this subject and after reading literary 50 posts on this subject i didn't see and answer to my specific question.
So please no smart remarks about an extra oil thread.

What do you recommend for my application ?
Thanks

 

[HT32BSX115]

Re: Oil viscosity for 89 350 King Cobra

BTW I did a search on this subject and after reading literary 50 posts on this subject i didn't see and answer to my specific question.

You're not going to get a specific answer either.

EVERY oil has been tried with satisfactory results.

If you do not want to use whatever OMC, Volvo or Mercruiser suggests to use, use what ever you want.

It all works.


regards,


Rick

 

[jerryjerry05]

Re: Oil viscosity for 89 350 King Cobra

The factory has been doing this a LOT longer than your buddies.I always found they know best.J

 

[Lou C]

Re: Oil viscosity for 89 350 King Cobra

OMC said straight 30, Merc said 30 under 50* and 40 over 50*, or their 25/40, I have used both 30 and 40 in mine, if you do a lot of high rpm cruising, you could use the 40. I have used the 40 and have had no trouble starting in temps as low as 45*.
To me the main thing is not to use a conventional multi vis in a marine engine, I don't think they stay in grade as well as a straight weight. The HD oils that are diesel approved like Shell Rotella and Chervon Delo 400 are really good, I use the Delo straight 40...

 

[sw33ttooth]

Re: Oil viscosity for 89 350 King Cobra

bought my boat last fall broker said use rotella t 40 and my uncles friend who owns a body shop said the same thing i use my boat in 42-80 degree water dont have issues

 

[HT32BSX115]

Re: Oil viscosity for 89 350 King Cobra

bought my boat last fall broker said use rotella t 40 and my uncles friend who owns a body shop said the same thing i use my boat in 42-80 degree water dont have issues

With all due respect, a boat "Broker" and a "friend who owns a body shop" may know about the same as my Dog does about motor oils....(or anything else for that matter.....)

You're still just better off putting in what Merc/OMC/Volvo/GM Powertrain suggests to use.