Oil mixing questions

[jaurora]

Well I have a 1988 150hp rude that has the VRO disconnected. I have a 35 gallon fuel tank below deck. What I have been doing for a couple of trips is mixing the oil and gas in a 6 gallon tank then pouring it into the fill on the boat. This takes a long time to fill up 30+ gallons.

I guess my question is would it be safe enough to pour the oil in the fill for the tank then fill the tank with gas as this would be much faster. I was just worried about it not mixing as well as it does with the 6 gallon tank.

Any thoughts?

thank you

 

[Mike722]

Re: Oil mixing questions

If you trailer to the dock, I would think that would mix the fuel just as good. If you fill at the dock then I might be a little more concerned, but 30+ gallons flowing in, I would think it would mix.

Someone else might have a different take

 

[Silvertip]

Re: Oil mixing questions

The only problem with adding oil first is getting the correct amount in. If you plan on pumping 30 gallons of fuel for example, and you first put in 5 pints of oil -- what happens if the tank has a little more fuel than you anticipated and can only get 20 or even 25 gallons in. You now have one or two pints more oil than needed. Won't hurt anything but it will smoke more and you are using more oil than necessary. My thoughts are to add 2 pints, pump 12 gallons, add one more pint, pump six gallons, or whatever combination you choose. In other words -- sneak up on it. Since you have a trailer boat, mixing will occur as you leave the gas station.

 

[rickdb1boat]

Re: Oil mixing questions

The oil mixes with the fuel very rapidly. I used to just make an educated guess on the amount of fuel that the tank would hold and add the appropriate amount of oil first. Then fill it up with fuel and add more oil if nessesary. There's always room for more oil after the pump clicks off..

 

[Cricket Too]

Re: Oil mixing questions

Wow a 150hp sucking on a 35 gallon tank, must not last you too long.

Anyway, I always fill at a gas dock on the water and pre-mix. I usually get 50 gallons when I get gas, so I just pull up, dump the oil in and then fill up 50 gallons, the fuel flows in pretty quick from a pump and will do the mixing for you, but I usually rock the boat a bit when I'm done. I usually add some Startron or something also, so I rock it a bit to give a little mix.

If you are trailering then I wouldn't worry at all. I did that for years as well and never had any problems. 2 stroke oil is made to mix very easily in fuel.

Silvertip has a good point, if you dump the oil in first just make sure you can get enough fuel in there to make it 50:1. If you know your always gonna take 30 gallons then it's no problem. I know I will always take the 50 gallons so dumping a whole gallon in first is no big deal.

The oil measuring containers are very helpful too, you can find them at West Marine or anywhere. They have different scales on side for different ratios, just go by the 50:1 scale, they have different lines for different amounts of fuel, just fill it up with oil to the 10 gallon mark and dump it in, and do it 3 times, then pump 30 gallons and you all set.

 

[aim4gold]

Re: Oil mixing questions

I have a 40 gal tank, I usually guess the oil on the shy side ? fill ?er up and then add more ail if needed. You have plenty of gas in the fuel line and filter. The boat rocking as you leave the dock is sufficient to mix the oil. Benn doing that on my 1987 since it was new ? no problems.

 

[dajohnson53]

Re: Oil mixing questions

First, there is absolutely no problem in pouring in oil and adding gas. The trick is estimating how much oil is needed. Filling from a gas station will provide enough force and agitation to mix up the oil. Driving to the ramp will also do it.

Is this a tank you can dip? If so, make yourself a dipping stick which is accurate in 6 gallon increments. Store it in a reasonably clean place. I did it by starting with an empty tank and a clean stick of appropriate size. I went to the gas station and added 6 gallons at a time and then dipped and marked the stick. Frankly, even though your tank is 35 gallons, I'd look at it as a 36 gallon tank, 6 multiples of 6. (each "6 gallon mark" would be more like 5.8 gal, no big deal). Mine are 25, but I pretty much use them as 24 gal. tanks for this reason.

Then, before I fill, I dip the tank and add oil depending on how much. I round to the nearest 6 gallons/1 pt (1/2 qt) oil increments. Because of the way I tend to "round up", this leads to mixing pints of oil for as little as 5 gallons (40:1) or possibly as much as 7 gallons (55:1). I sincerely believe that any oil mixture between 40:1 and 55:1 is not going to damage your engine or performance. The extremes are rarely the case, and if so, not constantly. My guess is that my fuel is generally mixed between 45-50:1. I also don't worry about completely filling the tank if it happens to be less than full when rounding to 6 gallon "units".

I'm not proposing wild inaccuracy, just that I don't think it needs to be like titration in the chemistry lab.

Of course, you could use a measuring container and get it more exact, but I just don't think it's that important. Hope that makes sense.

If you can't dip, you need another way of estimating how much fuel is needed. If you're totally going blind, you could add a pint, 6 gallons of gas from the pump, add another pint + 6 gallons, etc, until full. But I'd still recommend not being totally hung up (within reason!) with being overly precise.

Just one opinion - I've never had a problem attributable to my method of fuel mixing (Had others, but never problems because of the gas/oil mixture!)