721 Oil Capacity

[721Proxs]

How much oil does the tank on the 721 hold? I have googled to no avail...

[fishin couillon]

One description i just saw sys 3 Gallons or maybe it starts spilling out at 3 gals.

https://www.greatlakesskipper.com/me...-and-harnesses

[721Proxs]

I wished I knew for sure. I was out on the lake one weekend and the low oil warning came up on the mercury smart gauge. Said it had less than a gallon in it. I bought (got ripped off) a gallon ($42) at the only tackle shop close and of course it spilled out of the funnel before I could get the whole gallon in. I went back and fished for the rest of day. The next trip I made some top end passes and the warning came on again....

[fishin couillon]

Exactly what gauges and do you have a sensor for the tank? I know when i installed my Mercmonitor it would show low oil but there was no sensor so that option had to be turned off on monitor.....just a something to research.....

By the way, thats about average price for me unless i buy in bulk amd its $33/gal....even Academy has it for 39.99...

[721Proxs]

I buy the Mercury oil at my local Phoenix dealer, $26 when you bring your own jug. I will have to see what gauges they are, I don't like them at all though, I wished it had the regular gauges. They have recalibrated/replaced the trim sensor like 4 times now and it still dos not work right. I want to say they are the SC1000 line...I have a pic here somewhere if that would help.

[kry29]

Post in the merc forum. It's a mercury oil tank. They can help you get the gauges set up right and help with any issues. Just make sure you have all your info or they will get all soup nazi on you

[fishin couillon]

Post in the merc forum. It's a mercury oil tank. They can help you get the gauges set up right and help with any issues. Just make sure you have all your info or they will get all soup nazi on you

[721Proxs]

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[fishin couillon]

If you dont have the oil level sensor you should be able to turn it off on the gauge. Double check for that and then look in your manual. It will tell you there or like said make a post on the Merc page but make sure you add your motor serial number.

[721Proxs]

It has a sensor, was all installed when the boat was ordered from dealership new.

[fishin couillon]

Ok...does it need to be calibrated?

[hogbronzeback]

Check the oil level in the small onboard tank under the cowling. That needs to be full as well. That’s where the alarm sensor float is.

[duncankopprichardson]

https://domo-online.com/5-gallon-cas...y-optimax-oil/

[tmoney]

I believe the oil tank on my 721 holds 2.5 gallons. That's with me filling it just below the top-line, which is what I was told to do because the oil can expand.

[sthomasIV]

My sensor float got oil logged and would not read correctly. Warranty replaced it and after some adjusting the float by bending the wire slightly it reads very accurate. Never fill oil above top line on tank as it will cause your optimax to smoke like crazy until it uses some oil.

[06 SB]

It is 3 gallons. There is. 1.5 gallon but it is tiny and is not used on bass boats unless it was specifically requested. I had this sensor in the oil tank one time and it was notoriously inaccurate and always gave a low oil warnings. I got sick of it and just went into my Mercmonitor and changed the Tank 2 (Oil) to not installed.

[haus9393]

10 liters. So 2.5 gallons

[Mgfan58]

Make sure the float hasn't turned sideways in the tank. It has to run with the length of the tank to even be close. My locking ring wasn't tight enough and it worked sideways on me. I did the same thing with over filling the tank when the alarm kept going off on the Mercmonitor. In the tank, it just has a regular float for the level and I'm not sure how accurate it is, but I'm not sure you can calibrate it either.

[721Proxs]

Thanks all, It will be at dealership this week, so I will have them check it out...


Duncan, that's the oil I get at dealership for $26...Good stuff