I can't think of two topics that get AR owners fired up more than discussing "What is the best Zero for your AR?" and "What is the best lube for your AR?". Its kind of like discussing politics and religion with your liberal relatives at the Thanksgiving Dinner table. So here goes - I use a 50/200 zero and lube with Mobile 1 Synthetic Oil and Mobile 1 Synthetic Grease. "She" likes to run hot and wet! ps. There is no "best" - it's what works for you.