How much oil do I mix with gasoline for my 22 25cc 2cycle bush wacker gas hedge trimmer?

The easiest way is to mix it in your gas can as you buy gas at the service station.
If it's a 2cycle, most of the oil mix I buy says on it that stabilizer is included in the oil mix. Fuel stabilizer does not take the place of your 2cycle oil mix. I haven't ever had problems with my 2cycle gas going bad even when left for awhile.
If it's a 4cycle you can mix the stabilizer in when you buy gas.
For now, guess at the fuel tank size ( a quart ? ) and work out the ratio to add to the trimmer tank. A teaspoon maybe. A little too much won't kill anything.

Echo 1500 hedge trimmer
Kathy, Gas mixture 50:1, with mid or premium gas.
Check the attached links,manual,instruction and guides, Good luck
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http://www.echo-usa.com/getattachment/f9348047-25e4-468f-b298-f5927ec23249 2 Cycle Oil Mix Chart
Small Engine Repair How to Calculate or Mix 2 Stroke Oil with Gasoline or...

32 parts gas 1 part 40weight sae oil

did you know all 2cycle oil is 40W SAE? ?

Dye is added to it to fool everyone so they buy the colored oil

50:1 is 50:1 no matter whose 2 cycle mix you use. 50:1 is 2.6 ounces of 2cycle mix to 1 gallon (US) of gasoline. I recommend strongly to use a brand that contains fuel stabilizer. It will come in a 3.2 ounce bottle...still 50:1. The premium 2 cycle oils will be semi-synthetic or full synthetic and will claim "no smoke"

the Ryobi S430 is a 4 cycle engine. As such it has an oil reservoir which takes 30 weight oil. It uses straight gasoline in the gas tank.

50:1 mixture. Trimlite, Trim 'n Edge, and EasyReach models.
Pre-mix unleaded gasoline and 2-cycle engine oil in a clean 1 gallon container approved for gasoline.
Unleaded gasoline. Mix Homelite Premium Exact Mix oil with gasoline according to the instructions on the package. If Premium Exact Mix oil is not available, use a high quality 2-cycle engine oil, mixed at 2.6 oz. per gallon (US). Do not use automotive oil or 2-cycle outboard oil.
Homelite manuals are quite hard to find. I'm sorry that I can't help you with that.

Mix one ounce of 2 cycle oil per quart or 4 ounces of oil per gallon of unleaded gasoline. Hope this helps and best wishes.

it is 2cycle i run mine at 50:1

you can use a 40:1 mix if it smokes then cut it back to 32:1 but a little more oil is better than not enough so start with the 40:1