What weight oil should I use on my 460 King Cobra

[Striper Blues]

I just had a new long block installed and the mechanic recommended 25-40 weight. Sounds thick but I'm guessing these big engines work hard... Any one back this up or have another suggestion?<br /><br />thanks,<br />Pat

 

[trog100]

Re: What weight oil should I use on my 460 King Cobra

sounds about right.. the mercruiser stuff claims to be a blend of 25 and 40 oils i think..<br /><br />does sound a bit thick for a new tight engine thow as u say.. u either use a little thinner stuff to run it in or go with the usual recomendations..<br /><br />trog100

 

[waterone1@aol.com]

Re: What weight oil should I use on my 460 King Cobra

It used to be that straight 30 or 40 weight was recomended. Now merc is suggesting 25W40. Unless you are running in the dead of winter, I don't see any harm in using the 25W40 even in a new tight engine. Remember to follow break in recomendations....not to do any sustained high rpm operation and not to stay at any rpm for any length of time.

 

[seahorse5]

Re: What weight oil should I use on my 460 King Cobra

The OMC Cobra and King Cobra engines had a factory recommendation of 30W oil for normal use.

 

[tvbjr]

Re: What weight oil should I use on my 460 King Cobra

Seahorse is correct,the mannual for my 1990 460 king cobra says to use 30W

 

[trog100]

Re: What weight oil should I use on my 460 King Cobra

the interesting thing about the merc stuff is that it isnt described as "multigrade" oil say 25/40.. its actually described as a blend of 25 and 40 oils.. which to me is just a clever way of saying straight 30-ish oil.. depending exactly what ratio the 25 and 40 oils are mixed of course.. i am guessing the mix would be about fifty--fifty.. <br /><br />a true multigrade 25/40 would be based on a straight 25 oil with additives added to to give it the same viscosity when hot as a straight 40 grade oil..<br /><br />i always pay carefull attention to manufacturers exact wording.. perhaps i shouldnt.. he he <br /><br />the stuff merc sell to put in the outdrive is also a straight 30 based engine oil with some additive to keep water in suspension.. not the thicker 70-80-90 based gear oil as most folks including me would have imagined..<br /><br />trog100

 

[Boatin Bob]

Re: What weight oil should I use on my 460 King Cobra

I've got a pair of 460 KC's and I've always used the OMC 4 cycle oil which is really just 30W.

 

[Striper Blues]

Re: What weight oil should I use on my 460 King Cobra

Thanks guys, you help is much appreciated. I'll look for th 25/40 and use 30 if I can't find it.<br /><br />Pat