Adding olive oil to pasta water will not keep it from sticking together.
The key is the amount of water that you use. As a rule of thumb use 4 quarts for the first half pound and another quart for the second half pound. I don’t cook much more than a pound at time since that’s eight servings. I use at minimum 3 quarts of water for even a single two ounce serving of pasta.
It is critical to have your sauce ready and sauce the pasta the minute that it is finished draining.