While Garden motors happily put Quartz 9000 in my car...i bought filter from them..as thats what they demanded for warranty book stamping, the agreed that 5w-30 is much more appropriate grade than their 5w-50. Logic given was that..Taglon will never cause sludge..even we change oil after 8000km. Also said that Taglon is actually thinner than regular 5w-50:) i still don't understand what exactly this means? Is their 5w-50 different to mobil1 5w-50 lol then if viscosity is different, what the hell are they selling? If blended by ExxonMobil, then its should be a standard.