bcbouy
Well-known member
i have a johnson 9.9 i mix it 50:1 but on the motor it says 100:1 that seems high to me . what do you guys mix at? i dont know the year of my motor,but its the newer style with the thermostat on the top of the block.
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mix ratio
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bulldog
Well-known member
I mix 50 to 1. I would not mix 100 to 1 if I were you. Pretty lean IOM.
mtnwkr
Well-known member
I have the same decal on my '86. This is what I found in the webs. I run mine 50:1. This is a great site on these motors... https://www.sschapterpsa.com/ramblings/OMC/OMC info.htm
From 1985 to 1988, OMC actually recommended a 100:1 mix, this was written on a decal placed on motors of these years. Observed on one 1985 Evinrude 9.9hp short shaft, there was a sticker on the powerhead cover next to the fuel line connection which shows a few cartoon icons of a gas can, and oil drop, showing a ratio of 100:1 for the fuel to oil ratio.
Apparently there was some problems with some motor users & OMC issued a Technical Bulletin #2162 dated March 1986, for the mechanics to remove the 100:1 decal, replace it with a 50:1 new decal & inform the owner, when the motor was serviced in an OMC repair shop. This was recommended for rental, commercial & heavy duty service engines. The factory did replace some damaged power-heads because of this. Apparently some motors, under the right (or wrong) conditions , if ran at a high RPM or under a load for extended periods of time, may seize due to lack of adequate internal lubrication. There was another bulletin sent out in September of 1988 that kind of soft pedals around the issue, for a link to this bulletin #2211 CLICK HERE.
Back when OMC re-introduced their 50:1 ratio of oil, an old time marine mechanic was told by factory engineers that many of their motors would survive on 100:1 but they couldn't trust people to measure it accurately or control what kind or the amount of oil they used. So they held it to 50:1 ratio. The 100:1 was sufficient lubrication for most motors while running. The bulletin had nothing to do with lubrication while running and everything to do with storage of the motor. So the 50:1 you have a margin of safety in case of a lean carburetor on a multi carburetor motor or an overheat and it can still protect the clean internal parts while not used for a few months in a climate that can create internal sweating. It appears that the manufacturer's lawyers were very careful to not create the situation where a possible class action lawsuit could be presented, so they emphasized the storage internal lubrication theory where the average boater could not dispute it.
From 1985 to 1988, OMC actually recommended a 100:1 mix, this was written on a decal placed on motors of these years. Observed on one 1985 Evinrude 9.9hp short shaft, there was a sticker on the powerhead cover next to the fuel line connection which shows a few cartoon icons of a gas can, and oil drop, showing a ratio of 100:1 for the fuel to oil ratio.
Apparently there was some problems with some motor users & OMC issued a Technical Bulletin #2162 dated March 1986, for the mechanics to remove the 100:1 decal, replace it with a 50:1 new decal & inform the owner, when the motor was serviced in an OMC repair shop. This was recommended for rental, commercial & heavy duty service engines. The factory did replace some damaged power-heads because of this. Apparently some motors, under the right (or wrong) conditions , if ran at a high RPM or under a load for extended periods of time, may seize due to lack of adequate internal lubrication. There was another bulletin sent out in September of 1988 that kind of soft pedals around the issue, for a link to this bulletin #2211 CLICK HERE.
Back when OMC re-introduced their 50:1 ratio of oil, an old time marine mechanic was told by factory engineers that many of their motors would survive on 100:1 but they couldn't trust people to measure it accurately or control what kind or the amount of oil they used. So they held it to 50:1 ratio. The 100:1 was sufficient lubrication for most motors while running. The bulletin had nothing to do with lubrication while running and everything to do with storage of the motor. So the 50:1 you have a margin of safety in case of a lean carburetor on a multi carburetor motor or an overheat and it can still protect the clean internal parts while not used for a few months in a climate that can create internal sweating. It appears that the manufacturer's lawyers were very careful to not create the situation where a possible class action lawsuit could be presented, so they emphasized the storage internal lubrication theory where the average boater could not dispute it.
