So I’ve read about, on older Mercury engines, the oil injection being disabled and adding oil with the gas to avoid catastrophe in the event the oil injection were to fail.

 

Unless you are putting in a full tank of gas, do you just always have to “do some math” to ensure the right amount of oil for the amount of gas your putting in?  Although better than engine failure, this seem like a clunky way to do things...

What is your specific Merc engine; model, hp, year...?

Tom

20 minutes ago, WRB said:

What is your specific Merc engine; model, hp, year...?

Tom

I don’t really have one.  I just have read about it.  I think it mostly refers to 1990s model Mercurys.  I have seen this in several places online.

Yes each time you add gas you would have to add the appropriate amount  of oil to the gas. You would have to find out what ratio of gas to oil the motor requires to figure out how much oil to add. 

2-Stroke Oil Mix Calculator

• For a 50:1 ratio of gas to oil, use 2.6 fluid ounces of oil per gallon of gas.
• For a 40:1 mixture, use 3.2 fluid ounces of oil per gallon of gas.
• For a 32:1 mixture, use 4 fluid ounces of oil per gallon of gas.

10 minutes ago, kjfishman said:

Yes each time you add gas you would have to add the appropriate amount  of oil to the gas. You would have to find out what ratio of gas to oil the motor requires to figure out how much oil to add. 

2-Stroke Oil Mix Calculator

• For a 50:1 ratio of gas to oil, use 2.6 fluid ounces of oil per gallon of gas.
• For a 40:1 mixture, use 3.2 fluid ounces of oil per gallon of gas.
• For a 32:1 mixture, use 4 fluid ounces of oil per gallon of gas.

Thanks I guess if you do it often enough it probably gets to be a no brained.

Doing the math isn't hard at all, but buying one of these makes it super simple. Find your mixing ratio, and fill with oil to the line that matches up with how much gas you're adding. 

https://www.walmart.com/ip/Seachoice-21000-Widemouth-2-Cycle-Engine-32-Ounce-Marine-Oil-to-Gas-Mixing-Container/32738925?wmlspartner=wlpa&selectedSellerId=282&adid=22222222227021669100&wl0=&wl1=g&wl2=c&wl3=42967870232&wl4=pla-81459849872&wl5=9019155&wl6=&wl7=&wl8=&wl9=pla&wl10=111838817&wl11=online&wl12=32738925&veh=sem&gclid=EAIaIQobChMIx8bQ94Cn6gIVB77ACh0RIgyHEAQYAyABEgLp2vD_BwE

On my Mercury 150 XR6 I removed my oil injection, after having a pump fail a previous Engine. Many say to keep it, and yes it can be reliable when maintained, even still I chose to remove it for peace of mind. You do need to remember to add oil before filling with gas, for some that might be an issue. For me it is not. With my engine when it had oil injection the throttle arm controlled the amount of oil at idle until about half throttle at 100:1. At about half throttle up to full throttle the mix goes to 50:1. When I get get behind a slow pontoon for two miles and I’m forced to lug my engine a bit, it’s at 50:1 all the time on pre mix. Idle, you can foul more plugs. Merc sells a block off kit to take up the correct volume in the pump area. The oil alarm gets removed as well. Pre mix isn’t for everyone, but it is for me. 

Before oil injection we always mixed gas to oil in another container and never added oil to gas in the boat.

Tom

16 hours ago, WRB said:

Before oil injection we always mixed gas to oil in another container and never added oil to gas in the boat.

Tom

That’s definitely the best way to do it. In a plastic container.