Too late, already had put the oil in. I have tried similar products in past years in non hybrid vehicles with no ill effects. May as well report my findings for whatever they are worth. First I noticed that at highway speeds exceeding 55 miles per hour, I am able to maintain around 45 mpg (normally highway means 39-40 mpg for me.) At lower speeds between 40-55 I notice less power and possibly a slight loss of MPG. Kind of washing out the positive. Again the increasing FE might just be the placebo effect and probably it is just the better FE for warmer temps. Yesterday after a 3 hour dinner and show, I proceeded to leave the restaurant and the ice did not turn on, I got worried and accelerated aggressively just to make sure nothing was wrong, I am starting to love warmer weather in my hybrid.