what engine oil should I use

[huffy]

I have a 1995 seaswirl 201 with a 5.0 engine. The owners manual says to use straight 30 wt. i called a boat shop & they said to use valvoline 15-40. I was wondering if it would be alright to use, even ithough the manual says 30 wt. I live in California & the boat is used @ a 5000 ft elevation 98% of the time. I don't know if this matters. The weather temp is anywhere from 25 to 90 degrees @ the lake.Any info would be greatly appreciated. Thanks

 

[Don S]

Re: what engine oil should I use

Either use what your owners manual suggests or pick your own poison.
It's just that simple
Every oil out there has been recommended by someone for some reason. Let me guess, the guy at your boatshop is a sales person and not a mechanic. right? They recommend what is on the shelf.

 

[huffy]

Re: what engine oil should I use

He is not a salesman. It is a boat repair shop. The oil specified is what they said they use. I will be changing the oil myself & was just wondering if I should use the 30 wt or the 15-40. Thanks

 

[danond]

Re: what engine oil should I use

Go with the manual. The engineers that identified the required oil type worked for the company that would be on the hook if all their engines wore out prematurely. Considering the manufacturer would prefer the engine last quite a while so they can advertise their awesomeness, the service manual should be safe to follow.

Your mechanic apparently does not have the same incentive. If your engine never wears out, he never gets to repair it! Not saying he's crooked, just underscoring why the manufacturer isn't likely wrong.

 

[rjlipscomb]

Re: what engine oil should I use

The local weather report is nice, but when is the boat running? Summer when it feels good to get wet or winter when you have to break through the ice? I would suggest that you don't listen to advice that recommends blended oil for wide temperature swings like you car experiences. Boats are more frequently used when the weather is nice (I know there are a few old salts on here that will disagree with that statement). Stick with the manufacturer's recommendations:redface:

 

[Fishermark]

Re: what engine oil should I use

Like Don mentions, if you want to use something other than what the manual calls for, you will get every imaginable oil recommended by someone.

My opinion, for what is is worth , is that things change.

Your owner's manual was written around 15 years ago. Technologies and oil formulations change. I don't know what you have, but here is the latest recommendation from Mercruiser:

 

[Dryon]

Re: what engine oil should I use

Here is what the FC-W means & what the boat owner needs to be aware of:

FC-W? Four-Stroke Oil Certification Program
With the widespread introduction of the four-stroke outboard engine technology, NMMA considered it necessary to develop a marine engine oil category specifically for marine four-stroke engines. With all of the major outboard engine manufacturers producing four-stroke outboards to further reduce emissions and increase fuel economy, the need for oil specifically designed for the unique marine environment became necessary.

Industry leaders in lubrication developed testing criteria for this marine four-stroke oil. These include bench tests for viscosity, corrosion, filter plugging, foaming and aeration. In addition, the oil must successfully pass a 100-hour general performance engine test.

Once these oils have been tested by a sanctioned test laboratory, NMMA will issue licenses for the oil's formulation and registers approved brands.

FC-W? lubricants have demonstrated the necessary performance and quality needed need in today's high performance four-stroke engines. The next time you are purchasing four-stroke oil for your marine engine, look for the FC-W? trademark.

 

[Dryon]

Re: what engine oil should I use

OME Manuals do contain a whealth of information and anyone considering working on their boats should have them, but manufactures do revise them and those revisions are issued as TSB's. Oil technology is constantly changing and boat owners need to stay updated on the changes. What was written even ten yaers ago could be outdated.

 

[Rocky_Road]

Re: what engine oil should I use

OME Manuals do contain a whealth of information and anyone considering working on their boats should have them, but manufactures do revise them and those revisions are issued as TSB's. Oil technology is constantly changing and boat owners need to stay updated on the changes. What was written even ten yaers ago could be outdated.

Exactly.

Thinking that an oil recommendation, that is decades old, is the 'best'...is no different than saying that the Earth is flat, since that theory worked fine while it lasted.

As for temperature swings...here in the Florida Panhandle, I have launched the boat at dawn (46 degrees), and by 1 pm the temperature had reached within the 70's...sometimes higher.

I use the newest recommendation (25w40, FC-W)...and my Earth is round (egg shaped, to be correct)!

 

[bruceb58]

Re: what engine oil should I use

Air temp has little or nothing to do with it. The engine is water cooled...

Uhh...actually is does make a difference. Cold start conditions.

 

[Rocky_Road]

Re: what engine oil should I use

Air temp has little or nothing to do with it. The engine is water cooled...

I guess that Mercury missed this one...since their chart is based upon AIR TEMPERATURE. I wonder what else they missed...maybe it's time to go get a Volvo?

Reread my post...I haven't told anyone what to use. That includes you.

I told you what I use...and why.

Peace,
John

 

[Gary H NC]

Re: what engine oil should I use

My 2 cents! Straight 30 weight has never failed me....Delvac or Rotella T..
Dang good oil and half the price of the Merc oils...
I am saying no more....

 

[bruceb58]

Re: what engine oil should I use

No, sorry. What most fail to understand is that when you put the boat in the water, the engine is below the water line and the water passages are filled with water before you ever touch the starter.

I disagree...next time you trailer your boat to the water and drop it in, measure the temp of the engine. If its 32 degrees outside, the engine is going to be 32 degrees. The engine is not going to warm up fast dropping it in the water. it is a huge mass. The recommendations are for all conditions for all boaters. That is why they have an air temp chart.

 

[rjlipscomb]

Re: what engine oil should I use

Hey, I don't know much. I grew up building street cars as a kid. Multi-weight oil was a big deal given the extreme temp conditions under which people drive cars. In the winter, its cold and the engine is just as cold when you start it. It warms up to 195 or 210 degrees and runs all day. Multi-weight made good sense.

Boats? It seems to me, being not that smart, that boats are generally used when the environment is warmer (air and water), though once the water starts flowing thru the engine, the engine will reach the water temp quickly and start rising from there. That's my penny's worth of advice.

The manufacturer employs engineers to design the engine and systems. They are smarter than me and probably design all of the well tested internal components and lubricants to work together as a "system". Changing one, impacts other parts.

Oil technology has changed over the years. Oil viscosity is more stable at various temps and use. Additives and cleaners have improved.

Call me silly, but I kinda think the manufacturer knows more than me. Unless, of course, he changes his mind and sends me a technical update (bulletin).

Your call, follow your heart, you're the own that has to pay the price if wrong...

 

[IVAZ]

Re: what engine oil should I use

Yall can use whatever silly viscosity yall want but, when yall are ready for real performance use this:

Good for everything. You can even drink it to ease pain if you want.

 

[huffy]

Re: what engine oil should I use

thanks for all the info & feedback. Will be going with manufacturers recomendation. once again to all Thanks

 

[QC]

Re: what engine oil should I use

I can not think of any marine engine I've torn down that was damaged by an oil failure or wear due to poor lubrication with the exception of having no oil in it.

I knew I loved you man . . . I have mentioned this in these godforsaken oil threads for as long as I can remember. Truck business myself for 30 years. Seen stuff splattered all over the place; contamination, running them out, or whatever, yes, all the time. But I have never seen a failure blamed on the oil itself. Oh, and how many times do we see a guy on here saying I think I spun a bearing?" Or "I think I just ate a cam lobe." Or, "my turbo bearings are . . . oh . . . wait . . . no turbos, that's why we don't see that here, check.

It's manifolds, and blocks and water pumps and over heats and trim pumps and wiring and ignition and faults and . . . ad infawhatever . . . These are not lube failures. If this topic deserves that much attention I am missing the upside completely . . .

P.S. I also like Don's latest, "Either use what your owners manual suggests or pick your own poison." . . . Perfect.

 

[Lou C]

Re: what engine oil should I use

Well I used the OMC recommended straight 30 in my 21 year old 4.3 and it does just fine....rather than guessing based on what a particular shop tells you....use the recommended oil and then pay attention to the results...do you have normal oil pressure with the engine both cold and hot....do you have quiet lifters and normal oil pressure after a long hot run....if yes then the oil is obviously right for that application....I think a straight weight is pretty much always better for a marine engine than multi vis oils...that's why the Merc 25/40 is not a true multi vis....you don't want the VI improvers that are used in traditional multi vis oils....marine engines are under load all the time not like automotive engines....and as long as your coldest cold start is at 30 degrees or so...a straight 30 will still allow you to start as long as your battery is OK.

 

[enginesilo]

Re: what engine oil should I use

Just changed my own oil today and went with the recommended Mercruiser 25w40 oil. Figured I couldn't go wrong with the actual Mercruiser brand oil that was specified.

 

[stonyloam]

Re: what engine oil should I use

My "470" manual (20+ years old) says 40 wt., but my Mercruiser dealer (he should know) says Quicksilver 25-40, so that is what I use. So check with your dealer to find out what the current recommendation is.