We now recommend 20w50 and you can use synthetic if you would like to.
I would stick to any name brand quality oil.
Do not use Lubrizol additive with either of the oil types when using 20w50.
As to the instructions, they are in the back of your parts manual.
You can download your parts manual here > http://www.hustlerturf.com/images/pr...als/302612.pdf