What octane do you run in your boat?

churchy · Posted: Jun 25, 2004 8:35 am Post subject: What octane do you run in your boat?

I have an 01 Wakesetter VLX w/ the Indmar 325HP engine. I have always used 91 octane gas... Is this really necessary? Pros and cons of lower octane?? What are you all using?

Johnny5 · Criminal Joined: 17 Apr 2004 Posts: 82

I used super duper premium (94 octane) in my MC (Indmar) because I just figured you should.
Then a friend told me that MC recommends reg grade (89).
I tried it out it was fine and I have been running it since then and I have noticed no change in my engine temp, power pulling, etc...
At the prices today it is worth it to try, and if you are paranoid take along a can of octane boost, if you notice any detonation etc then dump it in.
Cheers

Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

Check your manual. I'm pretty sure it will recommend 89 octane. I run 89 in my indmar without a problem.

Good luck

FatBoy · Outlaw Joined: 27 Feb 2004 Posts: 143

surfsup · Outlaw Joined: 30 Jan 2004 Posts: 118 City: Orlando

87 in my PCM Excalibur...

Styk33 · Posted: Jun 25, 2004 10:46 am Post subject:

87 in my Mercruiser. If it doesn't ping, no need for more octane.

blur · Criminal Joined: 22 Apr 2003 Posts: 97 City: Littleton

91, but depending on your engine it may not make sense running high octane. most mercruisers were made to run on 87. I have a Marine Power and the ECM will actually adjust to whatever octane you throw in. so I run 91.

Neognosis · Ladies Man Joined: 13 Jan 2003 Posts: 17617 City: Webster

I fill it with 87. At half empty, I refill with 89. Then when half empty again, I refill with 87. Half again, 89, and on and on.

No problems.

mcfatty · Addict Joined: 13 Jan 2003 Posts: 725 City: Cookeville

churchy · Posted: Jun 25, 2004 12:11 pm Post subject:

mcfatty, Rock out with your #*&% out is old school....

mcfatty · Addict Joined: 13 Jan 2003 Posts: 725 City: Cookeville

I thought it was something somebody had just made up that day. They said it as I was swimming in to do my pass and I thought I'd drown laughing.

bigonboatin · Newbie Joined: 11 Apr 2004 Posts: 41 City: spring lake

92 my boat is old

jklein · Posted: Jun 25, 2004 2:08 pm Post subject:

I'll run 89 if it's cheap enough. However, if I fill up at Sams Club or Costco they don't have 89, just 91 at a lower price than most gas stations' 89.

Indmar too.

Ruune · Posted: Jun 25, 2004 3:19 pm Post subject:

2004 MAG MPI... Mercruiser recommends 87, so thats what I use.

Pumpkin Head · Outlaw Joined: 01 Aug 2003 Posts: 127 City: Oregon

chaz28o · Posted: Jun 25, 2004 5:39 pm Post subject:

Unless your compression ratio is 10:1 or better - you're wasting your money buying higher octane

Octane is for anti-knock - and if you're below double digit compression, anything over 87 is wasting money

whiteVLX · Newbie Joined: 22 Jun 2003 Posts: 32

Churcy-> I have the exact same boat and I run 87, I've never put in 89.

jbt200 · Posted: Jun 26, 2004 9:06 pm Post subject:

better gas will make the engine last longer.... burn cleaner less problems....premium always 93

vette74 · Posted: Jun 28, 2004 6:06 am Post subject:

jbt200,

tryan · Soul Rider Joined: 06 Feb 2003 Posts: 257

what vette said. less performance with higher octane.

read your manual or follow the label on the motor. period.

now if your marina is not selling much fuel, stored fuel looses one octane point per month. we have two marinas. one has 93 octane for 215.9 and the other sells 89 for 232.9. you figure that out. the low octane/ high price marina has above ground tanks with water/condensate issues.

i don't buy lake fuel, unless it's just a gallon or two to get me back to the trailer. and yes, i buy premium for my 30+ year old boats.

if you have a carbon problem, pinging or pinking, i would recommend decarbing the motor. all smokers (2-cycle/outboard) should decarb at the end of every season. if you idle a carbed inboard ALOT, you might do it every couple years or so.

Broccoli B · Posted: Jun 28, 2004 9:35 am Post subject:

If you do a search on this topic i made a real long post on why in 99.9% of cases the lower octane the better. vette74 has the right idea though.

I run 87 in my 320 indmar. I would run lower if i could find it from a reputable station.

P.S. in MI at my local sams club 87 octane in $1.799

gobeer net · Outlaw Joined: 11 Jun 2004 Posts: 116 City: Fort Smith

I work in the service department of a Chevy Dealership. We've seen trucks in the past that start to miss. When a person comes in with a one year old truck, and its already idling rough....they get pissed, and I dont blame them. When we diagnose it, it often comes down to the injectors. After we ask them what gas they use they answer, "Oh, I only run the best, Premium grade only!". This usually ends up being the problem. Higher octane has a high flash point as mentioned above. Its made for high compression motors to stop or lessen detination. From what i've been told its basically the same as 87 octane but with additives to slow the burn rate. So 93 octane is 87 with "junk" in it. I say junk cause for < 10.0:1 compression motor is doesn't help it, so its just in the way. Also, our usually fix is running our procedure for cleaning injectors then make sure they run 2-3 tankfulls of 87 octane. If the problem persists we replace injectors, but this almost always fixes it.

just my .02

Rock Toy · Outlaw Joined: 07 Feb 2003 Posts: 105 City: San Francisco

It never ceases to amaze me how people think that higher octane is "better" gas. Bottom line is that the higher the octane, the more stable the fuel is. "Pinging" occurs when the fuel is detonating before the compression stroke is at its peak. That's bad Mr. Green

If you are not pinging, you don't need more stable fuel so run the cheap stuff and you'll be fine.

BTW, I have never heard of switching fuel octanes between fill-ups?!?!? Sounds like someone is pulling your leg.... Laughing

Calabria man · Posted: Jun 28, 2004 12:24 pm Post subject:

87 works in my 04 Mercruiser 350 Mag MPI

JR · Soul Rider Joined: 14 Dec 2003 Posts: 473 City: ATX

kyle · Guest

i use 93 in the SAN and i used 93 in our X-Star when it was our x-star

JR · Soul Rider Joined: 14 Dec 2003 Posts: 473 City: ATX

89 Octane as stated in my Owner's Manual. 700 hours...

ssrgeoff · Addict Joined: 13 Nov 2003 Posts: 582 City: So Cal

I was told 87 w/ GM Vortec 335

Alan C · Soul Rider Joined: 26 Jan 2004 Posts: 329 City: Calgary

i use 87... theres no point in wasteing my money (dads money) on a more expensive fuel

LFADAM · Posted: Jun 29, 2004 9:57 am Post subject:

89 octane for the 88 four winns, all marinas at my lake got 89

Chains Required · Newbie Joined: 29 Jun 2004 Posts: 48 City: San Carlos

I have my motor serviced at sea level and when I visit a lake above 2000’, I like to run a higher-octane fuel. I have always thought the higher octane would balance out the thinner air. Is this not true?

wkbdpremier135 · Criminal Joined: 19 Jun 2004 Posts: 71 City: Sarasota

I put 89 in mine

PortlandBrder · Soul Rider Joined: 18 Apr 2004 Posts: 352 City: Portland

This is a great topic, so many different views, I've been running 91 for the last 3 years. After reading this post Im putting 87 from now on in my Mastercraft.

Grace B. · Posted: Jul 01, 2004 10:58 am Post subject:

I use 87 in the Nautique. I really don't see a point in spending the extra money on a higher octane gas, the boat runs great with the 87.

vette74 · Posted: Jul 01, 2004 11:14 am Post subject: