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I just removed my oil injection on my two stroke merc 175. I know that the mixture is 50/1, but what is the best way to figure out the amount of oil needed and best way to add? I have a 70 gallon tank and usually spend about 40 gallons of gas on a regular day of fishing. I like to keep my gas tank full in storage. My thought to fill and mix oil is to fill the tank at the pump, take a 5 gallon jerry can caculate the amount of oil needed, pour into the jerry can and add another gallon of gas to mix. Is there a better way?
I have been spoiled by direct injection over the years, but I hear that Merc's oil injection in the early 90's can fail fairly commonly.
I'm back to doing the same thing after the failure of the injection pump on my circa 1998 OMC 50. Much easier when you only have a 12 gal tank & add the oil to jugs then dump into the tank.
I still don't get the reason for disconnecting it. It seems like a big hassle for no real gain. Does anyone here have any firsthand knowledge of a Mercury oil injection system failing resulting in engine failure? If you just disconnected it now, doesn't that mean it's been working properly for 15 years or so?
Which is more likely - a failure of the oil injection, or human error in making a mixing mistake?
Since you prefer mixing and this is a free country, there are a few ways to make it easier. First, you can buy 6 gallon jerry cans instead of 5 gallon ones, premix them, and then use these to fill up your boat. Alternatively, buy a mixing cup with marks for 50:1 ratio. They list 1 gallon increments on the cup. Fill up the boat, not the number of gallons, and use the cup to add the correct amount of oil.
I bought gas when the needle showed 1/4 - always put in 24 gallons and always added 2 quarts of oil. (which is a 48:1 oil ratio - perfect) That brought me to a comfortable 3/4 full tank...
It sounds like you should be able to double that - 46-50 gallons of gas and a gallon jug of oil and you'll be fine. Someone told me to always go a tiny bit rich (48:1 instead of 50:1) on the oil and I never had a problem with it.
Just write it somewhere - 12 gal gas = 1 quart oil, 48 gal gas = 1 gal oil. Best if you dump the oil in first, as it'll mix better. This works fine as long as you can figure your gas usage to within 10-20 gallons... If you really have no idea how much you need to put in, you'll have to go by 6s or 12s at the end?
I purchased a small beaker called a "ratio-right" at boaters world. It is graduated and marked fo several different ratios from 100-1 to 24-1, and takes all the guesswork out! You can mix for 1 gallon up to 12 I believe for a 50-1 mix. Handy item!
AdamLotz - 4/14/2006 8:14 PM Someone told me to always go a tiny bit rich (48:1 instead of 50:1) on the oil and I never had a problem with it.
Whoever told you 48:1 is richer than 50:1 gave you bad info. While it is true that there will be moreOIL in your fuel mixture with 48:1 as opposed to 50:1, your fuel mixture will be leaner (ratio of fuel to air) with 48:1 as opposed to 50:1. Reason being, there's only so much fuel/oil that can travel through a carburetor's jets. When you increase the amount of oil, you've decreased the amount of fuel that's going through the jet, thus a LEANER fuel/air mixture, not the other way around. This is common knowledge for anyone that's a long time dirt bike rider. Also, aleaner fuel air mixture makes your engine run hotter.
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Tomcod 5 - 4/14/2006 8:31 PM I purchased a small beaker called a "ratio-right" at boaters world. It is graduated and marked fo several different ratios from 100-1 to 24-1, and takes all the guesswork out! You can mix for 1 gallon up to 12 I believe for a 50-1 mix. Handy item!
They also sell ratio-rite's in many motorcycle shops. At least the ones that sell dirt bikes. I got a few ratio-rite's in my garage myself.
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solarfry - 4/14/2006 10:19 PM The correct way is to add oil prior to gasoline. Not the other way around. It's in old 2 stroke service manuals that nobody reads but I do.
It's also common knowledge to any one that rides a dirt bike. At least those of us that have been riding prior to the 4 stoke revolution.
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solarfry - 4/14/2006 10:19 PM After you pour gasoline in you are supposed to shake the can to make sure the oil has mixed correctly.
No need to shake the can if you put the oil in prior to pumping. But go ahead if you need the exercise.
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solarfry - 4/14/2006 10:19 PM I would go back to the VRO or whatever Merc calls their oil mixer. it varies the oil mix according to engine speed.
VRO was OMC.
__________________ Grady White SeaFarer 226 w/Yamaha F225 - SOLD
I still don't get the reason for disconnecting it. It seems like a big hassle for no real gain. Does anyone here have any firsthand knowledge of a Mercury oil injection system failing resulting in engine failure? If you just disconnected it now, doesn't that mean it's been working properly for 15 years or so?
Which is more likely - a failure of the oil injection, or human error in making a mixing mistake?
The oil injection failure is actually common in the late 80's early 90's Merc V6. Bottom line is that it has a stainless gear meshing with a plastic gear. When/if the gears strip, the motor is already damaged by the time the warning alarm sounds. I know of a few guys this has happend to. My injection was original, and looking at it after removal shows considerable wear, glad I removed it! The aftermarket replacement is pricey, and requires extensive labor. I am using this motor for offshore fishing and want to reduce the possibility of failure. I am not excited to mix, but if that's the safest route so be it.
Ratio-Rite is THE way to go...I've also seen Accu-Mix...same thing...you'll know exactly how much oil to add depending on how much gas you just put in...used one B4 Honda on my Rude w/2 40 gal tanks...most boat dealers have 'em, plus Cabelas, BW and West...THINK i saw 'em in Wally Market...$3.99...piece of cake and eliminates the guess-work...
And I know EXACTLY why you diconnected your auto-oiler...There's a PLASTIC gear in that system that DOES have a history of failure... ...
AdamLotz - 4/14/2006 8:14 PM Someone told me to always go a tiny bit rich (48:1 instead of 50:1) on the oil and I never had a problem with it.*
Whoever told you 48:1 is richer than 50:1 gave you bad info. While it is true that there will be more*OIL in your fuel mixture with 48:1 as opposed to 50:1, your fuel mixture will be leaner (ratio of fuel to air) with 48:1 as opposed to 50:1. Reason being, there's only so much fuel/oil that can travel through a carburetor's jets. When you increase the amount of oil, you've decreased the amount of fuel that's going through the jet, thus a LEANER fuel/air mixture, not the other way around. This is common knowledge for anyone that's a long time dirt bike rider. Also, a*leaner fuel air mixture makes your engine run hotter.
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if this is the case then what happens during new engine break in period when it is advised to use double the oil?
AdamLotz - 4/14/2006 8:14 PM Someone told me to always go a tiny bit rich (48:1 instead of 50:1) on the oil and I never had a problem with it.
Quote:
Whoever told you 48:1 is richer than 50:1 gave you bad info. While it is true that there will be moreOIL in your fuel mixture with 48:1 as opposed to 50:1, your fuel mixture will be leaner (ratio of fuel to air) with 48:1 as opposed to 50:1. Reason being, there's only so much fuel/oil that can travel through a carburetor's jets. When you increase the amount of oil, you've decreased the amount of fuel that's going through the jet, thus a LEANER fuel/air mixture, not the other way around. This is common knowledge for anyone that's a long time dirt bike rider. Also, aleaner fuel air mixture makes your engine run hotter.
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if this is the case then what happens during new engine break in period when it is advised to use double the oil?
Not an "if", itIS the case. Here's why. A carburetor jet is a a fixed orfice. Since it is a fixed orfice, there isa limit in theamount offuel/oil mixture that can pass through that orfice. When the amount of oil is increased inthe fuel/oil mixture,that can only mean a decrease in the of fuel that is passing through that orfice. The end result is that there is less fuel (but more oil) per volume of air. Thus a leaner mixture (leaner meaning less fuel per volume of air). Theexpanation I just provided you with applies to carbureted two stroke engines in which the oil is being pre-mixed into the fuel.
__________________ Grady White SeaFarer 226 w/Yamaha F225 - SOLD
You don't have to add oil first and then gas. I realize some manuals stated this, but they are wiritng for the least common denominator. There are certain circumstances where it's ok to put metal in a microwave, but rather than speel out exactly when it's ok, the easy route for the manufacturer is to just say no metal period.
The reason for adding oil first as solarfry mentioned is legitimate - it's to ensure proper mixing. This covers them from letting someone fill an empty tnak will 60 gallons of gas, dumping in the required amount of oil, and then firing it up and going. Obvioulsy, you wouldn't be getting a 50:1 ratio in the first few minutes! That said, 2 stroke oil is formulated to mix readily. If it's easier to dump in the oil at the end you can do so, especially if the gas station is a bit of a trek from the ramp. To cover yourself, when you add the oil at the end, dump the oil and a small amount of gas in a small gas can, shake it, and then dump that in.
To test out that my way works for your own eyes, fill a 6 gallon container with straight gas. Then take the pint of oil and a small amount of gas in anohter container and shake it. Now very gently pour that gas/oil mix into the same 6 gallon container. Wait 30 seconds and pour some gas out of that 6 gallon container. I bet it's pretty well mixed.
AdamLotz - 4/14/2006 8:14 PM Someone told me to always go a tiny bit rich (48:1 instead of 50:1) on the oil and I never had a problem with it.*
Quote:
Whoever told you 48:1 is richer than 50:1 gave you bad info. While it is true that there will be more*OIL in your fuel mixture with 48:1 as opposed to 50:1, your fuel mixture will be leaner (ratio of fuel to air) with 48:1 as opposed to 50:1. Reason being, there's only so much fuel/oil that can travel through a carburetor's jets. When you increase the amount of oil, you've decreased the amount of fuel that's going through the jet, thus a LEANER fuel/air mixture, not the other way around. This is common knowledge for anyone that's a long time dirt bike rider. Also, a*leaner fuel air mixture makes your engine run hotter.
Quote:
if this is the case then what happens during new engine break in period when it is advised to use double the oil?
Not an "if", it*IS the case. Here's why. A carburetor jet is a a fixed orfice. Since it is a fixed orfice, there is*a limit in the*amount of*fuel/oil mixture that can pass through that orfice. When the amount of oil is increased in*the fuel/oil mixture,*that can only mean a decrease in the of fuel that is passing through that orfice. The end result is that there is less fuel (but more oil) per volume of air. Thus a leaner mixture (leaner meaning less fuel per volume of air). The*expanation I just provided you with applies to carbureted two stroke engines in which the oil is being pre-mixed into the fuel.
info like this is why i love tht so much. thanks for the explanation.
mixing oil best way? 
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