Mix gas in saw tank?

[Sprucegum]

I never mix the right amount of gas for the amount of saw work I get done. I either mix a gallon and use 1 pint or I mix a pint and then another one and another one and another one...

So why not mix the gas and oil right in the saw tank each time it runs dry?

Other than forgeting the oil and blowing the motor - what could go wrong?

[Alta]

The short answer is dont do it. In my experience most peole have enough trouble dividing 128 by ratio #'s and a piston and cylinder is around 200 bux for the parts if you are using a decent saw. Whats the capacity of your tank? Quick - do you knoww it? Whats the fuel mix ratio recommended by the manufacturer - know that? Are you correct? Now take your tank capacity (probably expressed in metric measurements) and figger out how many ounces of oil to mix in. Then figure out how to put that exact amount into the tank - gonna estimate by looking in the little bottle? And dont forget exactly how much oil is left over so you know what you are working with next time. Then mix it properly. Maybe fill the saw half way, shake it a bit, and top it off? Then do this every time you use the saw.  That or wing it and have it too rich to run well and develop carbon build up and thus hot spots, or too lean to survive very long before burning up your piston.  Ive spent way more time on this than its worth, only becasue it seems so obviously wrong that you probably need a very detailed description to keep you frorm doing this with a simple "dont do it" You probably will anyway but you cant say I didnt try. !

[beenthere]

Other than forgeting the oil and blowing the motor......what could go wrong?

Nothing, but you did answer your question..."what could go wrong?"

Alta said it well, IMO.    I don't have any problem with fairly long term storage of mixed gas in my Stihl saws, brush cutter, and pole trimmer. Maybe there is a gas conditioner in the oil for mix, but seems the doesn't change being on the shelf in the can, that I can tell.  I like topping the tank off when heading out to saw, and wouldn't want to be guessing how much is left in the tank that would need a specific amount of oil to be 'right'. 

[tcsmpsi]

Please, to understand, this is coming from a fellow who is still fine-tuning himself to some of the newfangled chainsaw gadgets/accessories/etc. he has come across in more recent years.

Things like, automatic oilers, anti-vibe engineering, heavy-duty 'featherweight' saws, designated chain/bar oil and this ONE thing that I have found most beneficial.   That little bottle of gas mix oil that's already measured out for a gallon of gasoline!! 

Since I have been driving chainsaws, that has got to be the most overall useful (to me) innovation.  Gallon of gas, bottle of oil, shake and pour.

I've never had any of it go bad.  Even at today's fuel prices,  if it weren't worth 5 bucks, it weren't worth cranking the saw.

[Phorester]

Mix a gallon, put in the right amount of conditioner, use what you need, put it up on a shelf.  If you wait so long before you use it the next time that the gas has gone bad, start all over.  I'd rather pay a few dollars for a gallon of new gas than risk ruining a chainsaw.

[Sprucegum]

Thanks for not stopping at the short answer.  :D

I appreciate your candor and obvious concern for the equipment, that's what makes this such a great forum.

And I solemnly swear I will not try to mix my gas in the saw.

[Alta]

Right - and I failed to mention that with Stihl oil at least, there is a fuel conditioner in the formula so it really isnt an issue. And nothing quite gets a burn pile going like old chainsaw gas and anyone with an old ford can also find a use for it so it shouldnt go to waste. I take care of about 20 saws for a fire dept and I see a lot of things that drive me absolutely nuts and this would too so if I seemed to over react a bit that might explain it. And I didnt even think about my beloved lil pole pruner...if anyone did that to that saw.....my goodness would there be hell to pay ;D ;D ;D

Driving chainsaws??????LMAO!

[Woodhog]

It is probably easier to just mix up the gallon . If you think you are not going to use it up before it gets bad, just dump it in your car....

[MotorSeven]

My .02.......I've also always run high(92-93) octane..it seems to last longer than the low grade stuff. I even run it in the enduro and wheelers.

RD 

[Raphael]

  All my saws run Stihl oil @ 50:1 and my big saws mill lumber and large timbers so I go through quite a lot of fuel.  I mix in a 5 gallon can adding 2.5gal at a time, I don't think the 5 gallon can has been completely emptied in over 3 years.  If it's sat a while I'll add a fresh 2.5gal (assuming it will fit).

[Pullinchips]

 uh oh, i can feel the octane wars starting up again.

-Nate

[MotorSeven]

uh oh, i can feel the octane wars starting up again.

-Nate

ooops, didn't know that nerve was exposed ;D  (kicking dirt back over it)

[KiwiCharlie]

Im with Woodhog - if for some reason my mix doesnt get used fairly fast, it goes straight in the car, and a fresh mix is made for the saws.
Charlie.

[rebocardo]

> Other than forgeting the oil and blowing the motor - what could go wrong?

Getting the ratios completely correct for such a small amount.

Say 12 oz of gas/50 = 0.24 oz?
Say 12 oz of gas/40 = 0.30 oz?

[Raphael]

  Also if you happen to need more than one tank of  fuel, mixing that second tank in a hot saw might have some rather dire consequences.  Best to avoid being the featured ingredient in sawyer flambe.   ;)

[Tony_T]

> Other than forgeting the oil and blowing the motor - what could go wrong?

Getting the ratios completely correct for such a small amount.

Say 12 oz of gas/50 = 0.24 oz?
Say 12 oz of gas/40 = 0.30 oz?

If you decide to mix such a small amount get yourself some graduated cylinders that chemists use.  First use it to fill you tank with mix so you know the EXACT capacity of your fuel tank (in CCs/mililiters).  Divide that by the ratio of your mix, this is the amount of oil that needs to be added (in CCs/mililiters).  Using a second smaller (and thus more accurate) graduated cylinder, pour the calculated amount of oil needed into the tank, rinse the graduated cylinder with raw gas into the tank then NEARLY top it off with raw gas,  SHAKE THE SAW LIKE HELL TO MIX THINGS UP, finish topping off then shake the saw again.

I don't do the above myself (tankfulls at a time) but I do use a graduated cylinder when measuring out oil for my mix, it's very accurate and I can calculate the amount needed exactly for any volume of gas, 1 gallon or 10.   

There are 3784 CCs/milliliters to a gallon. So for example a gallon of 50:1 :  3784 CCs gas/50 = 76 CCs oil

P.S. Yes , I'm a chemist........

[Sprucegum]

I finally got a solution I can work with - I found a 1 litre container with graduations on it and set of metric measuring spoons so I can do an accurate mix.

My Husky holds .6 litres and my old Homelite Bandit holds the rest  ;D  8)

Thanks again for all the input   

[Pullinchips]

AS people have said before.  We are talking about saws in the $400-600 range most of the time why chance a lean mix buy a 1gal mix bottle of good oil get a 1+ gal container mark saw gas and mix ratio on it so you know what it is for. Buy your choice of octange gas from your favorite retailer then pour bottle in rinse oil bottle with gas pour in container repeat if your a stickler and then add 1 gal of fresh pump gas (if you rather mix a tad richer go with .9 or .95 gals to make sure you have oil.  Then fill the saw up and use it for how ever long you feel comfortable with.  When you feel it is "bad" dump it in your truck.  This little residual oil in the partial gallon of gas mixed w/25 gals of gas or whatever your tank hold will not even be noticeable to your engine.  After all it is only a couple of ounces to the gallon to begin with.  This is a simple solution.  Dont mix in tank even though it can be done it is way to complicated and takes needless effort when you could be using your saw watching tv, boating, fishing, wrenching on something.

-Nate

[hondo]

Go get yourself a 2 1/2 gallon plastic gas jug from the hardware store. Use between 2.3 - 2.4 gallons of mid grade gas. When I say between 2.3 - 2.4 it's whenever it ends on some even amount of money at the pump, right now for me it's $7.00 even at $2.99 a gallon for mid grade. The saw isn't going to blow up if you're off a little here or there with a fraction of a gallon of gas. I use mid grade because high test was eating the diaphragm out of the carburetor.

Get yourself some mix oil made for 2 1/2 gallons of gas and dump in after gassing up the jug. I always add the oil after out of habit.

If you are not going to use up the gas right away put a little Sta-bil in it.