Hard to say. the newer 2 strokes like the optimax dont run an exact ratio. The computer adjusts the ratio based on what it thinks the motor needs. When i had a 115 optimax, it used very little oil, but that could have been the way that i ran it, too. More time on the trolling motor than the big motor.

I just used 2 1/2 gallons on the red and was running 128 miles a day for 4 days.

Thanks for the reply's. I was just a little POed today when I called the shop to check on the progress and they said they found/described the exact reasons I dropped off the boat with the exception of the excessive oil consumption. I felt like they were more interested in selling me a tune up!

Really sucks being boat less.

About 14 qts a year

You gotta realize you asked a question that really is very open ended. Basically you asked "how many fish do you catch in a year" type of question. Everyone's answer is different and it depends on many things like how often you go, how long you stay, how advanced of a fisherman you are, etc.

Someone telling you they only use 3 gallons of oil doesn't help you out a bit. This same person might only go fishing 3 times a year and only runs for 30 minutes each time. Another guy tells you he uses 30 gallons of oil. This guy lives on Toledo and fishes 5-6 days a week and runs an average of 45 each day. In other words, nether of these guys' answers would help you. You should've asked what ratio of oil to gas do you think your boat uses. Figured someone would've came on here and said that by now.

Telling us the current hours on the motor does little to help understand what's going on. Since you've stated that you have burned 15-20 gallons of oil "in a year" we need to know how many hours you put on the motor during THE SAME PERIOD, not the total hours on it now. (We must assume some of those hours could have been put on the motor prior to the beginning of the period that used 15 to 20 gallons of oil.)

We can, however, do some approximate reverse calculations for a properly working engine. I don't believe any variable oiling system goes richer than the 50:1 ballpark. So, let's use that as a worst case, assuming you run the [censored] out of it. Each gallon of oil would burn along with at least 50 gallons of fuel. That means that 15 gallons of oil would burn along with ~750 gallons of fuel. That is a HUGE annual amount of fuel to burn in a freshwater fishing boat rigged with a modern 125 HP outboard.

How much fuel do you use on each trip? (and how many trips per year?) ....or how many gallons do you typically buy and how often? That's the ballpark way to understand if 15-20 gallons is about right, or if there's something wrong. If you have any accurate data, it can indicate whether there's any chance the motor is over-oiling due to a defect. If you're just guessing, you may need to start keeping good info to back up your complaint.

My 2014 250 Pro XS had a leak at the oil pump that took the dealer 3 trips to find. It would run oil out the cowl and down the midsection. Take the cowl off and check inside the cowl to make sure you have no leaks. Mine went from using a ton to now I'm scared it isn't using enough. LOL And with the price of oil you don't need to be leaking it out.

It has a varible oiling ratio of 400 to one at an idle to 60 to one at WOT so depending on how you run the motor is going to dictate how much oil you use. The oiling is controlled by the PCM (powertrain control module)so the dealer should probably check that also. It was programmed to use more oil during breakin hours so it may still be stuck in that mode. What you need is a good honest Mercury mechanic.

40 to 1

Sounds like it is stuck in breakin mode using twice the normal amount of oil.

My Etec used about 9 gallons a year according to my calculations

LOL..still running an EFI. Oil and gas go through it like a firehose.

Gman

Here's how to use less oil: stop and drop a trolling motor once in a while!!!!

Right here - if you are using 1 gallon of oil to 27 gallons of gas, the plugs should be fouled, and the motor should smoke like a coal fired powerplant. that is an extremely rich mixture. So the question of are your burn rates higher than expected, the answer is yes almost double the rate you would expect a marine 2-stroke to burn oil.

The next question is 'why' and what do you do about it.

i have an old OMC with VRO, on that motor you can simply disconnect the VRO and pre-mix gas:oil at a 50:1 ratio. Not sure on your motor ...

Remember though - it's always better to burn fuel with too much oil in it than to burn fuel with not enough fuel in it. On these new motors I wouldn't be certain that a 1:50 ratio would be good enough. We all know that the computer sends a different ratio of oil:gas depending on RPM.

Pull the plugs and post picture of them. I would like to see them.