I’ve seen 4 or 5 variations of this marinade, and everyone seems to love it. I opted for less oil (a couple of recipes called for an entire cup). We thought it was pretty tasty. I might ease up a little on the soy next time, but not bad at all for an experiment. 
1 c Sprite
1/3 c soy sauce
2 T oil
1 T lemon juice
1 T mustard
1 T worcestershire sauce
1/4 t garlic
several grinds of pepper
Combine all ingredients. Pour over chicken (in a glass baking dish or a ziploc bag) and let marinate in the fridge about 6 hours (or overnight). Grill until no longer pink and juices run clear.
*One recipe I found said it works well for chicken, beef, and fish.
