The advantage's to Oil is that it's a good source that allows you to combine with different types of elements, such as katon. Combing the oil and katon will make the range of the blast go further as well as make the flames bigger when launching said attack. I also believe oil makes it slippery when shot out so it makes it difficult for the opponent to move. As for Syrup, it can be used with doton to harden up and make something into cement, keeping someone in place indefinitely. It's also good to use if you want to just get someone stuck somewhere since it's very sticky to my knowledge.Method 3 is completed finally. Next:
Method 4: Alternative Releases (Water/Oil/Syrup)
This method will be easy. Basically these are techniques that create a different substance than the water, however, they still fall within the category of Suiton release. They are liquids that possess different properties than ordinary water, for example: Oil and syrup. Oil is a flammable substance, one wouldn't use this to combat fire but rather fuel it, and with syrup you create a much stickier viscosity of liquid that doesn't necessarily flow as fast as water but it gives a more adhesive property to it.
This is a very unique version of Water Release. Most of them are spat from the mouth.
Advantages/Disadvantages of Method?
The disadvantage to oil is that if not used properly someone else could use it against you. Since you're releasing it from your mouth, it could give someone the chance to fire something back and it would explode/travel in you and cause some serious possible damage. As for syrup I believe the same principle applies since you're releasing it with your mouth, however, the difference being that is can get you stuck somewhere and then you'll just be a sitting duck.