Synthetic oil or not?

jeffk

jeffk

New Member
Apr 28, 2009
273
Sarasota, Florida
Boat Info
2006 300 Sundancer
Engines
5.0L Mercruiser w/Bravo III
Need to change the oils and such. Just used Mobil 1 in my 5.7GXI VP. Getting ready to do the same on my "New to Me" 2006 300 Mercruiser 5.0L. And opposing thoughts?
 
Ok, Thanks, Works for me!


sfergson727 said:
Plenty of discussions on this very subject in the past. I will say this. DO NOT use automotive oil in your marine engine, and use what the manual prescribes.

In my engines, I run full synthetic Mercury 25-40 oil, per the maint. manual. This is the oil you should run in yours.

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sfergson727 said:
Plenty of discussions on this very subject in the past. I will say this. DO NOT use automotive oil in your marine engine, and use what the manual prescribes.

In my engines, I run full synthetic Mercury 25-40 oil, per the maint. manual. This is the oil you should run in yours.

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On my 07 - 350 Mag manuals it says synthetic blend. My boat was built in 06. Interesting that yours say synthetic, wonder when your boat was built, mine was built in June of 06.
 
I agree with Scott but the problem in our area has been that the new oil is very difficult to find. No one has been able to tell me why exactly but I assume it's price or product availability? As soon as it become available, I will plan to use the syn oil, even if it is 2x the cost of the regular stuff.
 
You can get Corn Oil from Sam's for $5.00/gallon....

You all are getting ripped off...

Now where's that can of pledge for my strataglass and the velcro for my new rudder indicator?
 
Four Suns said:
You can get Corn Oil from Sam's for $5.00/gallon....

You all are getting ripped off...

Now where's that can of pledge for my strataglass and the velcro for my new rudder indicator?
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Fryolator oil is cheaper.
 
Delvac 5w-40 runs about 23.00 at walworld. My two cents on specific boat motor oils to everything else oils is this. Where my boat engines live and run is a nice dry bilge compared to the rain soaked, dirt splashed, and frozen, **** hole that my truck engines live in. Delvac is a HD syn. oil with all certs.
 
Not to start a oil discussion, since it appears that there is one happening. One thing that I noticed is the specs on the oil appear to be closer to diesel engine specs than auto oil specs. Not saying to use diesel motor oil... just an observation.

I use full syn in everything now... cars, truck, lawn cutter, and the boats. I may be over supporting the oil barrons, however i fell like I am doing something better for my motors and may actually sleep better at night. It's my wallet.
 
I'm using synthetics in everything I own as well. Good oil is good oil - however synthetics have shown to have better performance at temperature extremes and with overall wear. Which oil and what brand will quickly become a spiraling thread - I'd recommend the Mercruiser oil if you are still under warranty.

I'm using Amsoil 10w40 marine alone with their synthetic media filters (Ea) in my engines. For oil you need to understand the way it is rated. Take the 20w40 - 20w is the cold weather performance (or winter rating) which is what you'll get at start-up. The 40 weight is the running (at temperature rating - usually 190-200*) weight of the oil. I'm not sure I'd want to run the 20 or 25 weight at start-up even with the manufacturer recommending it. A 5 or 10 weight when cold is going to flow through the engine quicker and help reduce start-up wear.

Whatever you do - use an FC-W rated oil which tests for a variety of factors during a 100 hour run test. Corrosion prevention is a key part of marine oil which automotive oils do not protect against. Some will say if you change the oil frequently enough this isn't a factor but I'm not going to take the chance.
 
In 2006 I picked up 5 gallons of oil from my dealer. They all came in a burgandy bottle, 3 were synthetic blend with blue in the label and 2 were synthetic with green in the label and stated for outboards. I called mercury and after getting to the right person was told to only use the 25-40 synthetic blend in my inboard engines. The reason for this was due to moisture. That moisture will will stay on top of pure synthetic oil and will blend with the other not causing any harm to the engines. That pure synthetic was ok for outboards because they run hotter.

If you use the 25-40 synthetic blend you also need to use high efficiency oil filters.
 
In 2006 I picked up 5 gallons of oil from my dealer. They all came in a burgandy bottle, 3 were synthetic blend with blue in the label and 2 were synthetic with green in the label and stated for outboards. I called mercury and after getting to the right person was told to only use the 25-40 synthetic blend in my inboard engines. The reason for this was due to moisture. That moisture will will stay on top of pure synthetic oil and will blend with the other not causing any harm to the engines. That pure synthetic was ok for outboards because they run hotter.

If you use the 25-40 synthetic blend you also need to use high efficiency oil filters.
 
tdappleman said:
I'm using synthetics in everything I own as well. Good oil is good oil - however synthetics have shown to have better performance at temperature extremes and with overall wear. Which oil and what brand will quickly become a spiraling thread - I'd recommend the Mercruiser oil if you are still under warranty.
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Same here, synthetics in both cars and the boat. I am using the Mercuiser full synthetic for the boat. Only the best, over kill maybe, no cutting corners here.
 
sfergson727 said:
Jim, the synthetic that is referenced above is a new oil, out in 2009. For some reason, in mercury's wisdom, they made the label the same color as the outboard oil...only they know why, but it is not the same stuff as the outboard oil you reference above.
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When I purchased my oil last year I knew nothing about this new oil. I'll have to look into this. If you find the info, please post it. Thanks for the tip.
 
jimbo 84 said:
In 2006 I picked up 5 gallons of oil from my dealer. They all came in a burgandy bottle, 3 were synthetic blend with blue in the label and 2 were synthetic with green in the label and stated for outboards. I called mercury and after getting to the right person was told to only use the 25-40 synthetic blend in my inboard engines. The reason for this was due to moisture. That moisture will will stay on top of pure synthetic oil and will blend with the other not causing any harm to the engines. That pure synthetic was ok for outboards because they run hotter.

If you use the 25-40 synthetic blend you also need to use high efficiency oil filters.
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I didn't know you were suppose to use the high efficiency oil filter with Synthetic blend as well. I wish mercury would be a little better labeling their boxes.
 
The high efficiency filter isn't necessarily a requirement just because of synthetic oil. It really comes down to oil change intervals and is probably more relevant to those who run their oils longer than normal. With some automotive oils going beyond 7500 miles, a standard filter will not last that long and will require changing prior to the oil going the full duration expected. I use it simply to get a better filter media - synthetic vs. paper in the case of K&N, Mobil 1 and Amsoil Ea filters.
 
Mercury MerCruiser Oil Meets New NMMA FC-W Specifications

Press ReleasesFri
04
Sep
2009
For Immediate Release

FOND DU LAC, Wis. (Sept. 1, 2009) – With the National Marine Manufacturers Association’s new FC-W (Catalyst Compatible)™ certification going into effect September 1, 2009, Mercury Marine is proud to announce that its Full Synthetic SAE 20W40 engine oil already meets the new requirements and is FC-W (Catalyst Compatible)™ certified.
“Our Full Synthetic 20W40 MerCruiser oil was introduced two years ago with catalyzed engines in mind – it’s more environmentally friendly and makes no compromises on performance or corrosion protection,” said Eric Schlegel, Mercury’s Category Director – Aftermarket Products. “With the emergence of catalyzed marine engines, this new standard will help ensure that boat owners are directed to the right oil that protects both their engine and the environment.”
Compared to the existing FC-W™ standard, the new specification ─ among other requirements ─ limits the amount of phosphorous and silicon content to prevent catalyst and oxygen sensor fouling. With some states currently, and the entire U.S. in 2010, requiring certain new sterndrive / inboard gas marine engines to be equipped with a catalytic converter, it is critical for consumers to recognize that long-term use of oils not meeting the new FC-W (Catalyst Compatible)™ standard could cause engine damage that may not be covered under warranty.
Consumers can purchase Mercury’s Full Synthetic SAE 20W40 oil at their local Mercury Marine dealer.
 
Until my last change in September, always used recommended Mercruiser oil 25-40. This time used the 25-40 synthetic blend, but next time this spring full synthetic 20-40 as posted. As the old saying goes "pay me now or really pay me later"!
 
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