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View Full Version : What gas should I use in my new x2


Rsteenson
04-12-2012, 12:19 AM
I just purchased my first mastercraft. I live in a small town and eastern north dakota, and the only available octanes are 87 and 89 with ten percent ethanol added. There are other gas stations on the way to the lake, should I avoid my two options here and seek out 91 octane? What is the reccomended octane?

AZX9
04-12-2012, 12:26 AM
Not sure how "new" your new boat is but my owners manual (2003) says to use 89 in every engine produced that year. If yours is new and made by Ilmor that could be a different story. I doubt they would call for Super unleaded. They will however limit you On ethanol content. Lower the better. Ethanol attracts water from the air.

Rsteenson
04-12-2012, 12:44 AM
Apologies, its not brand new, just new to me. Its a 2008 with the mcx 350. Picking it up on sat. So I dont have a manual yet, just alot of questions going through my head.

AZX9
04-12-2012, 12:53 AM
I've got the MCX also and the manual says 89.

Jerseydave
04-12-2012, 03:33 AM
I run 89 in my MCX as recommended, no problems.

Latin Flyer
04-12-2012, 09:48 AM
Octane is not going to be the issue. Ethanol is!!!!
If you are going to put fuel with ethanol and not use it over a month it will slowly become an issue. It will not happen overnight, but ethanol will start to absorb water.
Suggestions
Ethanol free is of course the better option or
Put fuel before riding, not after, and try to keep it as low as possible.
I have mix feelings on ethanol additives, i did npt du enough research as i,m lucky to have ethanol free close to home, not on the way, but worth the time spent

wrobins1
04-12-2012, 10:00 AM
Octane is not going to be the issue. Ethanol is!!!!
If you are going to put fuel with ethanol and not use it over a month it will slowly become an issue. It will not happen overnight, but ethanol will start to absorb water.
Suggestions
Ethanol free is of course the better option or
Put fuel before riding, not after, and try to keep it as low as possible.
I have mix feelings on ethanol additives, i did npt du enough research as i,m lucky to have ethanol free close to home, not on the way, but worth the time spent

Not to scare you or overwhelm you but be careful on running the boat under 1/4 tank often seeing as the fuel pumps use the fuel in the tank to help keep them from overheating. There are countless threads explaining this better and they are worth reading.

CumberlandXstar
04-12-2012, 10:24 AM
I run 89 all the time in my MCX, but I do notice a little better acceleration with 91. I have my boat weighted pretty hard to the point that I sometimes have to dump ballast to get on plane. So if you are running it hard, I would go 91, but if you are just runnning it normal you will have no problems with 89.

scott023
04-12-2012, 01:20 PM
I was told at the factory that all '08 should use 89 octane.

BrooksfamX2
04-12-2012, 03:22 PM
Octane is not going to be the issue. Ethanol is!!!!
..........

Octane is a $$$ issue if you are buying a higher octane than needed. Many people think that the higher the octain, the beter an engine will run. Not always the case. Most newer engines are tuned to run regular 89 octane fuel.

scott023
04-12-2012, 03:24 PM
Octane is a $$$ issue if you are buying a higher octane than needed. Many people think that the higher the octain, the beter an engine will run. Not always the case. Most newer engines are tuned to run regular 89 octane fuel.

Nail, meet head.

SilviaMan
04-12-2012, 03:36 PM
Although the higher octane won't hurt anything.
I run highest octane available and lead additive, but my situation is way different than most on here it seems. With the age of my boat, there is a possibility that it was designed for leaded fuel.

jamisonsbrodie
04-12-2012, 03:36 PM
Depending on what lake area you are going to, Detroit lakes, Cormorant, Fergus? There are a number of gas stations around there that have non-oxygenated gas with 0 ethanol. 89 is fine to run, but like you said it has ethanol and over the long term, this will break down seals, gaskets, rubber gas lines and collect water. You probably won't notice an issue for years, but it will eventually show up. I try to run non-ox as much as possible, especially since I have a carb on my MC.

Jim@BAWS
04-12-2012, 03:58 PM
I just purchased my first mastercraft. I live in a small town and eastern north dakota, and the only available octanes are 87 and 89 with ten percent ethanol added. There are other gas stations on the way to the lake, should I avoid my two options here and seek out 91 octane? What is the reccomended octane?

AMERICAN MADE FUEL!!! NO CITGO, NO BP

USE HESS, SHELL or SUNOCO!!!

Important Fact..keep that fuel filter changed at the bottom of your fuel pump!
Do not run under a 1/4 tank...87 octane is just fine
If you at altitude bump up the octance...above 5000 feet

Enjoy your new boat...you are gonna LOVE IT!!!


Jim@BAWS

sleeporbutter
04-12-2012, 04:06 PM
Everyone has their opinion, but the manual calls for 89 so that's what I have used in my '08 and have never had an issue. I never run it below 1/4 also, because of the pump issues. I also use a marine ethanol treatment every time I fill up.

ntidsl
04-12-2012, 04:07 PM
Jim...87 is fine really??? That could save me $.10 per gallon this summer. Please confirm that wasn't a typo.

davidstan
04-12-2012, 04:15 PM
Apologies, its not brand new, just new to me. Its a 2008 with the mcx 350. Picking it up on sat. So I dont have a manual yet, just alot of questions going through my head.

I have your engine and i use 87 but with no ethynol. This off lake gas station caters to boaters and their 100% dino gas is clean but a tad expensive. All the MC'ers around here do the same thing.

barefoot
04-12-2012, 09:05 PM
I use 87 octane 100% gasoline in my boat. It actually costs more than the 89 with ethanol added. Whenever I'm traveling with the boat, I try to put 100% pure...even if it's premium.

zamboniman
04-12-2012, 09:37 PM
Most if not all gas is made in the same refineries based on region.. source of crude may vary.

Fact.. Different brand gas can and is made in same refineries possibly by a different brand all together. For a given region blend the brands are differentiated by their additives. Which are added at time of transport (literally in the tanker truck like putting an additive in your own tank). In other words a BP refinery may be making gas for local region gas in different brands such as Shell, Hess, Sunoco.

AMERICAN MADE FUEL!!! NO CITGO, NO BP

USE HESS, SHELL or SUNOCO!!!

Important Fact..keep that fuel filter changed at the bottom of your fuel pump!
Do not run under a 1/4 tank...87 octane is just fine
If you at altitude bump up the octance...above 5000 feet

Enjoy your new boat...you are gonna LOVE IT!!!


Jim@BAWS

Jeff d
04-12-2012, 11:08 PM
For those saying that their MCX manual calls for 89 octane does it say 89 "R+M/S"? Or does it say 89 "RON" or "Research Octane"

AZX9
04-12-2012, 11:20 PM
It says "89 octane minimum" it does not specify what method

CCAnderson
04-30-2012, 09:55 AM
Zamboniman is correct. Gasoline made by all refineries is made to a specification then transferred to the tank farms via pipeline. Essentially, a BP gas station has no idea which refinery made the gasoline they received because it was all mixed together at the tank farm. The station does know which additives were added into the tanker truck that delivered it. The refineries are not incentivized to make better than spec product because they will not be paid for it and it costs more to make.

As far as ethanol goes. Yes it does absorb water over time but it also a good cleaner. I run ethanol the first few tanks of the year to dissolve any varnish that may have deposited over the winter. Never had a problem in any engine: snowmobile, lawnmower, boat car, weed eater, tiller anything.

What it really comes down to is the energy content. 10 ethanol blends have abpout 97% of the energy content of 100 gasoline because ethanol has about 70% of the energy per gallon as gasoline. The savings you see at the pump in $/gal accounts for the lower energy content. You can test this at the pump with your car and use a cost per mile rather than mile per gallon and you will see numbers very close to each other for 90/10 and 100% gasoline. The math is a follows
1.0*.9 + .7 *0.1 = 0.97

In short. if you can it run 100% gasoline at the octane rating required for your engine but don't fret too much about ethanol. It will not destroy your engine even with repeated use. There were early issues with ethanol and gasket/o-ring failures but that has disappeared with advances in materials. Also, engines are designed for a certain octane rating and you do not get a benefit from burning premium fuel.

JohnE
04-30-2012, 06:47 PM
There was a thread a while back where it was explained in detail that if your boat calls for 89 octane then using 91 will not be beneficial. I will try to find it. Some motors are designed for 91 I believe. Maybe the lq9

Nutter281
04-30-2012, 10:04 PM
Also, engines are designed for a certain octane rating and you do not get a benefit from burning premium fuel.

I'm not sure that is true of newer engines. Peak horsepower is obtained from running just on the edge of fuel pre-detonation. Most modern engines use a knock sensor to advance engine timing to this point, or retard it depending upon the stress condition. Higher octane fuel is less volatile and can support higher degrees of timing advance. High 'lugging' type conditions are certainly the predominant environment for a boat during hole shot which can produce significant pre-detonation without retarding the timing.

Not sure how the ECMs work on our boats, but my 2009 F-150 FX4 with FlexFuel claims higher horsepower (only 5, but it is still worth mentioning) when running E-85. Of course the ECM can't tell what fuel I've put in the tank, but as the octane rating for E-85 is something like 100-105, the engine will advance the timing to take advantage of the reduce volatility of the fuel.

At the end of the day, I'm not sure how noticeable the difference between 87 and 91 octane would be, but I have to think for a ballasted boat, the timing retardation would make a significant difference getting out of the hole.

Austin

bcd
04-30-2012, 10:08 PM
Octane rating is the fuel's resistance to auto-combustion. A higher octane rating means the fuel can take a higher compression before it auto-ignites, which is also called knocking (burning before the spark plug fires) Octane rating has nothing to do with the energy or heating value of the fuel which equate to power.

Higher performance engines require higher octane because they generally have a higher compression ratio, or have a turbo or supercharger.

If an engine recommends 89 octane, it will not perform better using a 91 or 93 octane fuel.