Marine Grade Synthetic vs Automotive Grade Synthetic

Snowfish

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Is there any Real difference between marine grade & automotive grade synthetic oil?

I run Mobile 1 synthetic in my cars, trucks, etc. These are all obviously 4 strokes.

Any reason Not to run Mobile 1 in our 2004 60hp Merc BigFoot 4 stroke? Just another 4 stroke, eh?

I'm thinking the main difference is packaging & price. Thoughts?
 

JB

Honorary Moderator Emeritus
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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Synthetic oil is among the prime suspects in causing 4 stroke outboards to "make oil".
 

Chris1956

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Your Merc 4 cycle OB likely has a requirement for a FC-W rated oil. Mobil 1 likely does not meet that rating. I would recommend you stick with manufacturer FC-W rating.
 

Bamaman1

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

See BobIsTheOilGuy.com for everything you ever wanted to know about lubrication on about every motor ever made. You can read for hours on this website, as it's very interesting.

I think Mobil 1 would meet the rating, but the cost of obtaining the FC-W rating is not worth their time and trouble for relatively low volume marine oil.
 

Snowfish

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

That BobIsTheOilGuy.com is something else! Will take a bit to digest it all. This motor has run on synthetic all is life. Mobil 1 it is.
 

Chris1956

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

So your plan is to ignore the manufacturer's recommendation? An what is the upside to that plan? Do you save any $$?

Just so you know, Mercruiser recommends Automotive SAE 30 oil or the Quicksilver 25W-40 oil, because of the harsh loading inherent to marine engine operation. They do not recommend automotive multi-vis oil. Their engines are nearly exact production automobile engines, yet they specify special heavy duty oil. Your Four Cycle Outboard isn't even close in design to an automotive engine, but you think it acceptable to run an oil, that mercrusier didn't recommend.

Let me know how it works out for you. Just a data point for me...
 

Snowfish

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Good points. Fair enough.

10w30 is the recommended weight for my engine and climate. The "recommended" oil is Mercury 10w30 synthetic blend in which I can not find any real specifications. Just statements like "built to withstand the rigors of marine environment". Could very well be the same as the Mystic synthetic blend. Kind of like the Mystic gear lube is the same as Quick Silver gear lube. But that's a different story.............

The Mobil 1 10W30 is a full synthetic. All ratings are spelled out and approved for turbo & super charged engines as well. I like the lack of sludge, and burn deposits, on the internals of engines that have run full synthetic.

Cost is not an issue. We're only talking a quart or so. From the data that I've gathered, and lack of data availability of the Mercury private label, I'm thinking the Mobil 1 is superior oil.
 

Chris1956

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Snowfish, Just so you know, the Mercruiser 25-40 oil was supposed to be a blend of SAE 25 and SAE 40 oils, likely with some additives. Normal auto multi-vis is not a blend of different weight oils, but I believe it is a single weight oil, with an engineered molecule additive that causes the oil to get thicker as it warms up, overcoming the normal tendancy to thin out. The Mercruiser oil was supposed to be better at lubricating, under high load.

I am surprized your outboard does not specify FC-W oil. I still think that is what you should use. Did Merc put out an update to the oil requirements?
 

Snowfish

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Thank you Admiral Chris. You are a true gentleman. The last thing, that I wanted, was an oil debate. You provide straight talk, straight answers, comments, and insights. I salute you. And rightfully so since I'm way out ranked!

My engine Does specify the FC-W rating. From what I've gathered, the FC-W rating incorporates a higher salt spray corrosion test to pass. Heck, since I live in the "salt belt", our cars should use the same rated oils! LOL!

In addition, I find it interesting that we do not find Exxon Mobil on this list.

http://www.nmma.org/certification/certification/oil/fc-w.aspx

I'd be willing to bet that Exxon Mobil supplies the raw stock to many of the private labels. Then they add the additives to meet the FC-W standard. Or maybe it meets it already, but has not been tested by Exxon?

Since I'm not really a betting man or chemist, and the simple fact that I use phrases like "maybe, probably, and willing to bet", leads me to believe the best choice would be to stick with the proper genetic code.

Thank for thinking this through with me.
 

Outsider

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Use Amsoil and never look back. It meats all specifications except it isn't marketed by Mercury ... :eek:

Never heard of synthetic oil being the cause of 'making oil", always thought rings caused that by allowing fuel to pass to the crankcase. Live and learn ... :facepalm:
 

Chris1956

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Outsider, so Amsoil is a "meat" product? Sorry, show me the FC-W rating on the 4 cycle oil or the TC-WIII rating on the 2 cycle oil and I will consider it. Without those ratings, I cannot recommend it.
 

wired247

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Outsider, so Amsoil is a "meat" product? Sorry, show me the FC-W rating on the 4 cycle oil or the TC-WIII rating on the 2 cycle oil and I will consider it. Without those ratings, I cannot recommend it.

http://www.nmma.org/certification/certification/oil/fc-w.aspx

FB-30011B
AMSOIL Formula 4-Stroke Marine Synthetic 10W30 Motor Oil
AMSOIL, Inc.
FB-30012K
AMSOIL Formula 4-stroke Marine Synthetic 10W40 Motor Oil
AMSOIL, Inc.



http://www.nmma.org/assets/cabinets/Cabinet456/FC-W-2010-Mar11-2011.xls


Their 2 stroke oils are NOT TCW-III certified despite any claims they make on their packaging as to meeting TCW-III specifications.

http://www.nmma.org/assets/cabinets/Cabinet456/FC-W-2010-Mar11-2011.xls
 

Chris1956

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Re: Marine Grade Synthetic vs Automotive Grade Synthetic

Nice, so Amsoil stooped down to get a certification. Good for them....
 
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