I am trying to find out what type of gas is required in the Stihl sh56c

Wondering if you gave this list try.
Stihl 011 Parts

When you buy the 5L of unleaded Petrol (the same as a car uses), mix with the recommended amount of 2 stroke Stihl oil as marked on the container that the Stihl 2 stroke oil comes in.
Do not use any make of oil other than Stihl or Husqvarna 2 Stroke. I have come across so many people who have tried to cut corners by buying cheaper oil. If you are asking the question you are obviously not going to use the saw to cut down hundreds of trees so for a few pence/cents more for each fill, give the saw the best chance to last.
I always mix the can with 2 stroke oil as soon as I arrive home from the petrol station and MARK the can very obviously as 2 stroke. If you don't use the mixture within 1 month, it is a good idea to use it up in your garden mower. That is as long as the mower does not have a catalytic converter. It will work fine on the very weak oil mixture that modern saws require.

Try new gas, and adjust the carb.

If you clean it with a wire brush. you could try J-B weld, gas doesn't seem to bother it

You might try posting in the automotive section. You can get a manual from the manufacturer and look it up there.This is the plumbing pumps section not chain saws.

When started the leaf blower black gassy stuff came out of the muffler or the spark reflector what does this mean

20 to 1

Stihl chainsaws are 1:50 oil to gas ratio. Make sure you use good high-quality 2-stroke oil, preferably that which is made by Stihl.

go to your hardware store and ask for some 2 cycle 50:1 oil, mix that with a gallon of gas and you're good to go. Before you mix, make sure that you read the oil container for it's recommendations! You can purchase a small container of oil that is all measured for 1 gallon of gas