Mixing fuel and oil

[PrinceValium]

I know this has been brought up before and I did read some threads on it...however the answers were not adequate enough for me so I am going to ask the question again.

When mixing fuel with oil it makes sense to add the oil first and then the fuel to get some sort of mixing in the tank...and then the driving will help mix it until you get to the water. My thought is that I cannot add oil not knowing how much fuel I am going to be adding, so I add the oil last.

Is driving enough to disperse the oil in the tank sufficiently? I have a built in tank. Since buying this boat I noticed the fuel gauge is not accurate and reads low by 1/4 of a tank. I do not know exactly the capacity of the tank.

Will the oil mix ok or not?

Thanks!

 

[milehighboater]

Re: Mixing fuel and oil

I am going out an a limb here and saying yes. I will normally fill my tank about 6 gallons at a time, oil first then gas. I have the luxury of being able to open a hatch and see the fuel in my opaque tank and see if it will fit another 6 gallons. Now as far as oil then gas or vise versa I put oil in first so the gas will wash it though the fill tube and let driving do the mixing. Now that being said if you don't know how much gas you are going to use then I would say fill it up most of the way with gas, add your oil and top it off with one more gallon or so to wash out the fill tube. My only concern with adding the oil last without washing it through is the oil has a high viscosity and a good amout of it can remain in the tube where the swishing of the gas cannot get to it. After you get the oil in the tank it dissolves quite easily. So short answer, driving mixes gas well. Long answer... see above.

 

[verado7]

Re: Mixing fuel and oil

assuming you have portable plastic tanks - you can add the oil after and then shake up the tank with the vent closed -preferably.

if it is a permanent tank ( something i will never do on a 2 stroke ) it will still be okay - personally i would rock the boat back and forth - the only downfall with a permanent tank that i can see is - the oil would be somewhat concentated on teh bottom near the pickup so the motor will suck in some extra oil on the start - but once moving the tank will self mix -

i actually did this as a test when deciding to put in a permanent tank - i put the oil in last with out shaking the can and it was a tad smokier leaving the marina - so i concluded that there was a small concentration of oil around the pick up tube .

by the way if your not using a syntheticblend oil give it a try -less smoke and wear on the internals + you'll get a noticeable increase in bottom end as well as top end -

 

[milehighboater]

Re: Mixing fuel and oil

I'm sorry when I was writing I was assuming it was being trailered to the lake, I will say I did an on lake fill-up with a gas can and some oil and I was just about far enough out of the cove when my motor sucked a good amout of oil and stalled. No good... I would not recomend filling on the water either one first, I have not found a good way to mix in the tank at least not on the water, and I rocked the boat back and fourth quite a bit before I tried to take off.

 

[jerryjerry05]

Re: Mixing fuel and oil

Change the sender in the tank.The tank should have a sticker/tag on it telling you how much fuel it holds.
Since it already has some gas in it.Put in 1 qt oil then 12 gal.Or 1 pint then 6 gal. You might end up with a little extra oil every now and again.
But thats's better than not enough.My tank is 100gal so I just put in a gallon at a time.But paying for 48 gal can be fun at $2.75 gal.
Do a de-carb to loose the carbon every year.If you use the boat a lot do it more often.J

 

[8hygro]

Re: Mixing fuel and oil

Yes, driving the trailer around is sufficient for the oil and fuel to blend. Some pre-mix oils are more prone to fall out of suspension faster than others but it is always a good idea to sufficiently agitate any previous mixed fuel for thorough suspension before starting the engine. Blended fuels have compounded this scenario mostly because of thier ability to hold water.

8hygro

 

[waynelk]

Re: Mixing fuel and oil

I have a 25 gal. tank so if it's 1/4 full I put in oil for 15 gal. If it takes 17 or 19 I add the final amount of oil when it's full. Most is already mixed and the last bit mixes on the ride to the lake or bouncing in the water. I have 2 - 5 gallon cans I add oil to first and then siphon it into the main when needed, or you could top off after the 15 gal with premixed gas if you don't want to figure the oil for 2, 3, or 4 gal.

 

[sschefer]

Re: Mixing fuel and oil

My gas gauge is off too. I know when I'm down to 1/4 tank I've used about 10 gals of gas. I can only get 17 gals in the 20 gal tank so I put 16oz of oil in, then 5 gals of gas then another 16 oz and fill it up. Whatever over 10 gals it is I make up for with more oil. If it's a little under it won't make a huge difference so I leave it as is. I've never, never, not even once had a problem at the marina or anywhere else.

 

[arsenalpsu]

Re: Mixing fuel and oil

Driving is more than enough to mix. You and many people doing all this premixing are over thinking this. Do your self a favor and get a clear jug with gas in it, put a few drops of oil in it and watch how it mixes almost by it's self. You'd also be surprised how much one acceleration and brake will mix the tank. Oil or gas first it doesn't matter, and the small amount of oil left in the tub will make no difference.

You guys should be more concerned with water in your fuel- get a water separating filter and use Marine Stable in every fill up.

 

[PrinceValium]

Re: Mixing fuel and oil

Driving is more than enough to mix. You and many people doing all this premixing are over thinking this. Do your self a favor and get a clear jug with gas in it, put a few drops of oil in it and watch how it mixes almost by it's self. You'd also be surprised how much one acceleration and brake will mix the tank. Oil or gas first it doesn't matter, and the small amount of oil left in the tub will make no difference.

You guys should be more concerned with water in your fuel- get a water separating filter and use Marine Stable in every fill up.

I was actually about to do that very thing. When I go to the lake I usually have 5 gallon cans with me and mix it in those and then put it iin the boat. ( I am not going to pay 4.75/gal on the lake) My boat has a straight shot from the filler to the fuel tank so there is no filler tube that needs rinsing out etc.

The tank is built in and behind a wooden board. I have tire looking on top to see the fuel capacity but have not seen any markings. I dread having to pull at board in front of the tank as it also houses the speakers for this old boat.

I as out non the lake yesterday and the gauge was just above a 1/4 so I said we had better head back. We got close to the dock maybe 1/4 mile out and then the motor just shut down. I thought hoooooo I better not be out of gas already! ( this gauge seems to read 1/4 low usually) I pumped up the bulb again and took it easy coming in to the dock and it was fine. WHEW!

Ok here is another question. The mechanic I talked to said it is best to stick with the manufacturers oils rather than the ones from Walmart ( which I believe is Pennsoil synthetic) because of extra carbon build up they produce. He said it doesn't matter if it is Johnson or Quicksilver or whatever as long as it is the major brand oil.

What do you guys think?

 

[milehighboater]

Re: Mixing fuel and oil

I use the penzoil synthetic with no problems, no noticable difference between it and quicksilver that I can tell. Runs smooth, low smoke, and no more carbon buildup than when I was running any other oil.