I know many people will have asked this in the past but i need some advice. I went to buy some fuel at the LHS. My kids were getting wild in the store so i was being as quick as i could to get out the store. As i was in a hurry i picked up the wrong fuel i got 4 stroke instead of 2 stroke. it has 15% nitro which i always use but only 16% lube. OS recomened 18% lube to avoid damage to the engine. my question is can i just go ahead and add castor to the fuel to make up the 2 % the jug i bought is 1 gallon how much extra castor should i put in? the engine i have is an OS 46 MAX FXI thanks paul

Three ounces would be close enough!

Or you could just exchange the jug, or run a few clicks richer while burning the gallon.
Dennis-

i only pay $10.99 a gallon for sig fuel at my LHS but it would cost me $ gas in my car to exchange it thats why i was thinking of putting more oil in it

Paul, yes you can put oil in the fuel. Just be sure it is lube designed for a methanol base. most oils out there sold commercially are for petrolium bases. Castor oil would be the stuff to use. I just do not know if there is castor for methanol and petroluim. Or is castor good for both. I am not sure. So just be careful what you add. Good luck.

Mark Shuman

4-strokes need more oil then 2-strokes. Wilcat 2-stroke uses only 16% oil. 4-stroke starts at 18% or 20% oil. you can use the Sig fuel as is. Sig hasn't caught up with the new labeling. Dennis

As stated above, just add 3 to 4 ounces of degummed caster oil--not what you get at the local drug store.

While what you said might be true, every four stroke fuel I've ever seen contains LESS oil (16%) than most two stroke fuels (which usually have 18 to 20%).

I believe the theory behind it is, that two strokes fire every revolution (as opposed to every other) and therefore require the additional cooling provided by addional oil content.

Paul,
I was partly kidding because you've already heard that you can add 3 or so ounces of the proper castor oil to your fuel to make up the extra 2 to 4%, but you CAN simply run the engine richer and accomplish the same thing. (At a slight reduction in power and slightly higher consumption rate of course.)
Dennis-

Paul that 1 gallon is not going to kill your engine youll be fine