Which Oil To Use? 40 wt??

[jboatrider]

Hey everyone, its another oil question!

Looking to do an oil change this weekend on my Mercury outboard. 40 weight is required. Only including what I can get in close proximity in this poll since I'm trying to do it this weekend!! Don't really care about price either, boat runs like a top and I want to take care of it; plus one oil change per year. No idea what is in it now though since I just bought it and am new to the boating world.

Feel free to post below why you would use it too, might help in my decision making process.

Thanks in advance for everyone's response.

 

[jbcurt00]

What ever the owners manual for the motor says to use.

Since you said its a Merc, is the Merc oil in your poll the recommended oil?

 

[jboatrider]

Yes jbcurt00 it is. Well, it was originally a 1040 but changed when merc came out with this 2540 now.

 

[jbcurt00]

Use the recommended Merc oil then

 

[jboatrider]

Only issue I foresee is that I live in a kind of colder climate. Should I be concerned about that? Obviously I won't be using it in the winter but it will be colder when I put it in the water than probably a lot of others do.

 

[rallyart]

The important number is the 40, the non critical is the __W before it. You can use 0W- 40 to 25W-40 without issue. You don't need to, but I use pure synthetics. They start pumping faster and offer more protection if things go wrong. Some also have less drag on the engine. My first choice is Mobil1 5W-40 but any major brand is fine. I've tested several on a dynamometer and found that Amsoil had more drag than major company brands so I would skip that one.
If you leak or burn oil the synthetic will be worse for that.

 

[bruceb58]

If you leak or burn oil the synthetic will be worse for that.

That's a myth. Same weight will burn/leak the same no matter if it's synthetic or not.

 

[rallyart]

That's a myth. Same weight will burn/leak the same no matter if it's synthetic or not.

That statement is an error. The easier flow characteristics of synthetics go past seals faster when the engine is not running and can increase the rate of gasket leaks. I have lots of empirical evidence on that going changing both ways. Additionally, the cost is higher if any is burnt or leaks.

 

[bruceb58]

http://www.pennzoil.com/learn-about-...synthetic-oil/

Myth: You shouldn?t use synthetic oil in an older vehicle. The myth is rooted in the idea that synthetic oil is ?slipperier,? lower in viscosity, or not as compatible with seals and will therefore leak or leak more in places conventional oil might not. Again, completely untrue.

http://www.valvoline.com/auto-resour...yths-synthetic

https://www.youtube.com/watch?v=RpwrlWJMd40
time 2:30

 

[smokeonthewater]

See signature...

Use WHATEVER oil you want and change it often.... Frequent changes do FAR more good than high dollar oil.

 

[rallyart]

^ That statement, smokeonthewater, is very true in most situations.

 

[bruceb58]

For my Mercury Outboard, I use the oil that the manual recommends which is the Mercury 25W-40 synthetic blend.

I have never ever had any engine leak when using synthetic oil and these engines have been up to 250K.

 

[JoLin]

Only issue I foresee is that I live in a kind of colder climate. Should I be concerned about that? Obviously I won't be using it in the winter but it will be colder when I put it in the water than probably a lot of others do.

Merc specs their oil recommendations according to ambient temperature ranges, too. What do they say about which weight to use for your area?

If you're like most of the boaters here, your oil change is a once a year event. Whether the oil costs $15./gallon or $25/gal the cost differential is practically zero when factored into your overall cost of owning and operating the boat. My point being, why wouldn't you use what Merc recommends?

I kinda get a kick out of all the folks who believe they're qualified to second guess the people who designed and built the engines they're running.

My.02

 

[Chris1956]

Marine engines work far harder than automobile engines, whether they are sterndrives, inboards or outboard motors. Automotive oils also have a different rating system than marine engines.

Mercury normally recommends a FC-W motor oil, for it's four cycle marine engines (inboards, Sterndrives and outboards). That 25W-40 Mercury oil is likely rated FC-W. I would use that. If another oil is rated FC-W and it has a lower winter viscosity rating, it will likely work fine, as well.

 

[smokeonthewater]

Ya know... To clarify I figured it was understood that the oil needs to meet the manufacturer's specifications...

You don't need to, not does the manufacturer specify using their own brand as long as it meets their specifications, but it does indeed need to meet them.

 

[shrew]

Another vote for the recommended 25w40 as per the Merc manual. My personal rule of thumb regarding synthetic oil is, use whatever has been used in the engine since it was born. I won't switch. On new engine's I use synthetic or a synthetic blend. If the engine has never used synthetic then it never will. The biggest issues I've seen are older engine's that used non-synthetic for many years, then get switched over to synthetic. Those are the engines that appear to develop leaks. It's like the crud from non-synthetic plays a part in the gasket sealing process. Once the non-synthetic starts cleaning out the crud, the problems begin.

This is anecdotal and just one mans opinion.

 

[bruceb58]

More old wives tales!

You can always switch to a synthetic oil from using non synthetic oil and back and forth and not develop leaks.See the myth links in my post #9.

And since the Merc oil is a synthetic blend, that blows that theory out of the water as well!

I have used synthetic in many used cars that never had synthetic in them and they never developed leaks.

 

[WIMUSKY]

x? on using whatever the manual sez..... I'm a big fan of synthetics. I've also switched back and forth on the same engine.

 

[jboatrider]

Well, Mercury oil is not known to be a highly regarded oil is the issue. Not afraid of going against the owner's manual recommendation. Extremely concerning when the first non-Mercury content that pops up when I search Mercury 25W-40 is this:

MOD EDIT - No need to link to another forum. This thread will have all the oil misinformation anybody needs to form an opinion.

 

[bruceb58]

Well, Mercury oil is not known to be a highly regarded oil is the issue. Not afraid of going against the owner's manual recommendation. Extremely concerning when the first non-Mercury content that pops up when I search Mercury 25W-40 is this: http://forum.chaparralboats.com/inde...howtopic=17412

My bet is he was using the non-synthetic 25w-40 since he never mentioned it in his post. Mercury still offers a non-synthetic 25w40 oil.

What he saw is one if the reasons I believe in using synthetic oil. In one of the engines in a boat I used to own, if you used non synthetic oil, after you put more and more hours on the oil, the idle oil pressure would get lower and lower . With synthetic, the oil pressure would never change.