Gas for a 4.3

roffey

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Nov 22, 2012
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I did try and search this forum but could not find any answers, and I am sure this has been asked in the past. Can I run my new 2014 merc 4.3 on regular gas or do I use premium?
 

drrpm

Senior Chief Petty Officer
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Oct 24, 2008
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Regular gas is fine. I have good access to nonethanol so I use that.
 

WIMUSKY

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Ethanol wont have any negative effect on a new motor.....
 

roffey

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Nov 22, 2012
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I have not taken delivery yet. When I do they take me out for a water run and demo all the bells and whistles and fill me in on maintenance and use (gas would fall here). There will absolutely be an owners manual, I was just sitting here wondering what it would cost to fill. The difference between regular gas and super is about $20 per tank so I suspect I will use super and synthetic oil. Only the best for my girl,LOL. I have never paied this much cash for anything besides my house.

this is the boat I purchased, http://www.piratecovemarina.com/index.php/198-lx-str1057
I can;t waite just like a kid on Christmas day, LOL.
 

Silvertip

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Sep 22, 2003
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Some thoughts on this:
1) Higher octane (premium fuel) does not translate to more power. It's advantage is that it is less prone to detonation. properly tuned your engine will not have this issue.
2) Higher octane is advantageous only if the engine is fitted with a knock sensor that feeds the engine management system which in turn can automatically advance and retard timing as needed. Without this feature you are wasting money.
3) Premium fuel is required only in engines that have high compression and no means of automatically advancing and retarding timing based on engine load (again -- knock sensor needed).
4) If the manufacturer specifies premium, use premium. If they specify 87 - 89 octane, using anything other than that is a waste of money.
 

agallant80

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Oct 25, 2010
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My new merc has a sticker on it that says something about being certified to run on 87 pump gas.
 

H20Rat

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Mar 8, 2009
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Some thoughts on this:
1) Higher octane (premium fuel) does not translate to more power. It's advantage is that it is less prone to detonation. properly tuned your engine will not have this issue.

Its even worse than that... Premium fuel in an engine that doesn't have the compression to warrant it actually results in a very slight DECREASE in power. Usually not measurable and within the noise of a dyno, but still there. (octane lowers the BTU content of the gasoline)
 
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roffey

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Nov 22, 2012
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interesting, thanks for all the info above, but the synthetic oil is good?
 

Maclin

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May 27, 2007
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Good deal, excited for you! I will add to the consensus on 87 being the proper octane fuel.
 

Lager

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Jan 19, 2014
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Good advise so far and yes on the Synthetic oil.Concerning the fuel, the reg octane is ok but you might want to ad a fuel stabilizer for the ethanol fuel thats usually at your local pump. Its not needed if you use the boat a lot, but if its sits for months ? The alcohol can separate and cause all sorts of engine running problems.
 

Watermann

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Jan 12, 2013
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^^^ There goes your fuel cost savings! :lol:

Never will understand the mind set of spend thousands and then worry about 20 bucks but actually premium is what around 20 cents more a gallon and you have a 34 gallon tank... do the math, it isn't even worth worrying about at $6.80. If you look there's non-ethanol fuel out there and you won't have to worry about the corn juice fouling anything up. Every motor I have runs great on my choice of non-ethanol premium fuel, from my MC 4.3 LX to the Buick with the Northstar V8 and even the lawn mower.
 

smokeonthewater

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as for oil look at my sig..... If you REALLY want your motor to last forever CHANGE the oil often.....No matter what kind you choose.
 

bruceb58

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Mar 5, 2006
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Never will understand the mind set of spend thousands and then worry about 20 bucks but actually premium is what around 20 cents more a gallon and you have a 34 gallon tank... do the math, it isn't even worth worrying about at $6.80.
Never understood throwing money away...even only $6.80. Unless the engine can adjust it's timing, it's a waste of money.
 

roffey

Commander
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Nov 22, 2012
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I have spent a ton of cash on this boat and spending an extra $20 per tank is not a concern. Having said that I don't want to spend money where I don't have to. I intend on going with the manufacture recommendations and as Smoke said change the oil often, great advice.

one more sleep, then zoom zoom.
 

sickwilly

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Jul 9, 2007
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I run my older version of that boat on premium because my older version suffers from run on or dieseling if I run 87. Hopefully merc has solved that problem. If they have, run 87.
 

oldjeep

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May 17, 2010
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I run my older version of that boat on premium because my older version suffers from run on or dieseling if I run 87. Hopefully merc has solved that problem. If they have, run 87.

The carb boats like a little more octane. I had to run my carb 3.0L on 91 octane to get it to stop running on. The manual says 87 octane for his engine, which should have the electronics needed to keep it from knocking or running on with the recommended octane.

My new boat says 89, so that is what it gets 89 octane E10 - no issues so far using the recommended fuel.
 
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