What gas to run? 87, 92?

[ndemge]

1982 Celebrity 210 5.0L OMC230 (stringer i think)<br /><br />It's pretty slugish at the higher rpm range... I've only had it out once this year.<br />Last fall, it had about 15 gallons of gas in it, I added another 40 gallons of gas with stabilizer to top it off for the winter.<br /><br />It is at about a half tank right now, going out on the lake the next 2 weekends.<br /><br />Do these motors need higher octane gas? Here in MO, regular is 87, premium is 92.<br /><br />Plan on changing the fuel filter this weekend, who know's when/if the last time was.

 

[tmclendon]

Re: What gas to run? 87, 92?

The recomendation for my '83 is 89 Octane Leaded. I dump a can of lead substitute in 1 tank a year or so, even though most expertsa say is isn't really necesscary with these engines (Lead acts as a lubricant and some older engines will have valve seat problems if run on nolead for extended periods). One of the oil companies (Chevron??) has a web page dedicated to the subject, search the forums here and you'll find it.<br /><br />I use 89 in mine, runs fine.<br /><br />Tom

 

[snapperbait]

Re: What gas to run? 87, 92?

87 or 89 octane is fine... None of the OMC I/O engines produced at that time require anything more than 87 octane...<br /><br />Snake Bit's lead substitute's not a bad idea either..

 

[ndemge]

Re: What gas to run? 87, 92?

so anything more than regular is just a waste correct?<br /><br />..I do have a few cans of lead addative... might use em for a while.... <br /><br />I thought '76 is when they started using the hardend seets in the heads and you didn't need lead adative anymore... is this the same timeframe for marine engines?

 

[horndog]

Re: What gas to run? 87, 92?

running lead is a viable option if you are very over protective of your engine. You really don't know if they have hardened valve guides in those motors. Mine says 88 octane, but it doesn't state unleaded or leaded, and mine is a 1978

 

[ndemge]

Re: What gas to run? 87, 92?

well, I've got 4 cans of the stuff my dad gave me when I bought my '71 van.... but right after getting it, I rebuilt the motor and put on new heads... so now it's just sitting there.<br />might as well burn it up since I have it.<br /><br />going to try to run as much gas through it as I can next weekend. What a shame, gonna have to play all weekend

 

[DJ]

Re: What gas to run? 87, 92?

Any US built automotive based engine built after 1973 had hardened valve seats. Remember "low-lead" gas that came into existance before "no lead"?<br /><br />Dumping lead additive into it is doing absolutlety nothing but throwing toxins into the water and making your mind feel better.

 

[ndemge]

Re: What gas to run? 87, 92?

Thanks Djohns<br /><br />the lead addative will stay on the shelf.<br /><br />That part didn't even cross my mind..... not just going into the air, but into the water.

 

[anesthes]

Re: What gas to run? 87, 92?

Something to keep in mind. A motors octane requirements are directly related to the compression ratio, and temperature during operation.<br /><br />Also, a 5.0's small bore size helps fight detonation. <br /><br />-- Joe

 

[akriverrat]

Re: What gas to run? 87, 92?

and since carbon buildup and decreased cooling over time can increase octane needed, without symptoms till you burn a piston. running higher octane than timing advance calls for is insurance paid for at the gas pump.

 

[tmclendon]

Re: What gas to run? 87, 92?

Here's what Chevron has to say about it:<br /> http://www.chevron.com/prodserv/fuels/bulletin/unld-gas/ <br /><br />So according to them, any U.S. made engine made in 1974 or later will have no problem on unleaded.<br /><br />I'm not sure that the lead additive that I use is actually lead, seems to me it's labeled as a "Lead Substitute". <br /><br />Tom

 

[Boatist]

Re: What gas to run? 87, 92?

Ndemge<br />My 1980 140HP OMC owners manual call for LEADED fuel 87 octain or more. When could no longer get leaded fuel I ask the OMC factory rep at the boat show about what to do and he did advise me should be ok but may need to increase octain if get any pre ingition or pinging. I did have that problem and ran 89 with no problem at home but at the ocean had to go to 91. Had a bad valve due to exhaust manifold failure so pulled head and had repaired. also ask them to put in hardened seats if necessary so expected a big BILL but to my suprise they said not necessary and justed cleaned and replaced one exhaust valve. Since that time have had no problems with pre ingition even at sea level. Not sure why, could be becaused cleaned all the carbon out of engine or maybe new head gasket a little thicker, any now runs fine on 87 octain.