l have a 40 gal. gas tank and l want a 50:1 gas/oil ratio. It takes 16ozs oil to 6 gal of gas to get 50:1.l added gas and oil to the tank but not correctly. In the tank was 15 gals of gas at 50:1 and l added 25 gal of gas but l put too much oil to the tank (128ozs).How much gas/oil mixture will l need to remove from the tank so l can add fresh gas back to correct my mixture.

if you add too much oil the only thing that gonna happen is the motor will smoke more,,,and maybe dirty the plug faster.

Do not worry about it. Simply use the engine with the fuel as is. It will smoke more and want rev. as high, but unless you want to drain the tank completely, it will run.. In the old days the mfg. recommended double oil for the first 20 hours. You can fill up after a few hours of use, with high test if you like, but do not worry about the extra oil.

From my calculations u currently have 166oz of oil in the tank. For a correct blend u only need 103oz. With the 166oz to 40gals this gives u 30.85:1 ratio. So for every 30.85oz of gas that we remove from the tank, we should be removing 1oz of oil. We know we need to remove 63 oz of oil to have the 103oz remaining in the tank for a proper mix (103oz oil to 40 gals of gas) or (50:1). Multiplying 30.85oz x 63 oz = 1944oz. 1944oz / 128oz per gal = 15.2 gals. So removing 15.2 gals of gasoline from the tank should theoretically remove 63 oz of oil leaving 103 oz of oil in the tank. Then when the 15 gals. r replaced with straight gas ur tank should be blended to 50:1. 40 gals x 128 oz = 5120oz. 5120 oz / 50 ( blend ratio) = 102.4 oz. of oil. You should have 103 oz of oil remaining in the tank once removing the original 15 gals.

To make use of the gas that u removed u would need to add an additional 9.5 gals of gas to reduce it is ratio to 50:1. ( Then u have another half of a tank of mixed gas & nothing wasted.)

You have double oil not good> Take out 10 gal and add 10 gal gas without oil> Will smoke> Then when you add gas next add 10 with out oil with the 10 with double oil> Get new plugs for when your threw the plugs might fowl>

OK, so in theory u have 40 gallons of gas & 166 ounces of oil, right? (38 + 128) Meaning ur current tank is mixed 31: 1.

What u want is 40 gallons of gas & 102 ounces of oil.

So lets remove 15.5 gallons, that is 64 ounces of oil at 31:1, & top off with fresh gas.

Take that 15.5 gallons mixed 31:1 & add 9.5 gallons of fresh & u will have 25 gallons of 50:1 ready to go for next time.

What l do for my clients is build a worksheet in Excel that has the 50:1 ratio for all combinations of gas & oil. Laminate it & stick it in the glovebox for just such an occasion.

Best of luck.