u can use total cng oil... thats good.. i have been using it for quiet sometime and so complains till now... however sometimes when due to my utter laziness the oil gets changed over 5k... i get to flush the engine...
also do change the filter too...
another option is of petro canada oil. that this has money back guarantee of 10k+ km... which i guess is good... the price should be around 1100 per 4 liter///