Keep in mind the FX35 engine and FX45 engine react differently to octane changes. I have an FX45 and have owned VK35DE's in RevUp and non-revup form. The VK45 and rev-up VQ35 are very particular regarding fuel quality. The regular VQ35DE is not so much, and only recommends premium. The 45 and RevUp 35's require it, and in the manual state that if you cannot get premium fuel, to only get as much as is required to get to a station that does have premium fuel.
