Yup, Mobil 1. I put in 2 bottles of the "add anytime" stuff since my capacity is 8L and the proper ratio is 4:1. Called the Tech at Rislone as well. The company has been around for 80 years. He states there is no esters in the formula, but wouldn't specify further...the formula is secret..but, it is different from CD-2 Engine detergent. He id say that the blueness is just a die and that the qt. bottle works better as it has more of the base oil which is a "penetrating lubricant". 200 mi. so far. Will keep everyone posted.