Engine Oil

[AZPowerStroke]

I will be changing the oil in my boat this week and was wondering if I could get away with using 15W-40 as opposed to the Mercury 25W-40? Any thoughts? Thanks.

[typerider]

i think it'll be fine. check with a merc. dealer so you don't void your warranty using something other than stock stuff though. i know some car companies are pretty picky about things like that when it comes to power train warranties. not sure how mercruiser feels about it. otherwise i'd say a slight viscosity change like that shouldn't hurt anything.

[Razzman]

Just for the record guys, a manufacturer cannot void your warrenty for using an oil other than what they recommend. Under the Moss-Magnusen act it is illegal for them to do so. The only thing that can is the oil rating, example a mfgr says to run API SD rated oil and you run API SJ or Rotella (which is basically heavy equipment diesel oil, some people do it!) and they can verify you used the wrong oil then maybe. As long as you used the correct rated oil your ok. Now if the mfgr says use a multi-weight then by all means do as they're a lot more effective in wear tests. I run Mobil 1 10w30 in my boat and it works just fine.

[FIC]

They can void warranty if you do not change your oil on the reccommeded time .

[lee]

With a 2000 21v I do not think he has a warranty.

[typerider]

thanks for clearing that up Razzman i knew there was more to it than what i had said. lee is right overall though as usual = ) on a 2000 no mo warranty.

[AZPowerStroke]

Yup, warranty is long gone. I work on a lot of diesels and have tons of 15W-40 oil at my disposal. That's why I was wondering. So I should be all right using it instead of the 25W-40?

[Razzman]

I would think you'd be just fine.

[spharis]

I use straight 40W.

[Razzman]

There ya go! SP you just made my case! As long as the oil used is within the temperate range specified for the weight using then it makes no difference. In your case living where you do there's probably not a big temp flux during boating season so 40w works just fine.

[lee]

In our Merc engines we use 25-40 in our Marine Power engines we use 15-40.

[spharis]

There ya go! SP you just made my case! As long as the oil used is within the temperate range specified for the weight using then it makes no difference. In your case living where you do there's probably not a big temp flux during boating season so 40w works just fine.

LOL that and my valve guides are leaking.....40 weight keeps me from burning too much oil.....I'll have to replace them after a few dozen more hours.

[gman]

Marine power specifically states not to use multi viscosity oil. They state that either a straight 30 or 40 weight oil should be used.

[jsz]

I've heard (and use) 40 wt is fine for warm areas.

[typerider]

i've used straight 40 in mine and it was fine. i'm now using 25-40w again but if marine power suggests not using multi-viscosity why does the owner's manual specifically say to use it? anyone use synthetics? if so any difference? used it in my car then realized its not worth $$$ to be in "my car."