Do anyone use 5W-40 engine oil in their FX?

C

carguy75

Member
Location
alpharetta,ga
Hi. My FX seems to lose about 1-2 quarts of oil between oil changes. My FX do not smoke, but oil seems to disappear. I heard that this is a common problem with the older VK engines. I use Castrol Syntech 5W-30 oil. I read in the FSM that 10W-30 or 10W-40 can be used in warmer areas. I read on the Castrol Edge spec sheet that 5W-40 is thicker than 5W-30, but lighter than 10W-40. I was thinking about changing over to it, but want to know if someone else is using 5W-40 already and if they lost MPG and power by using it. If I use 5W-40 and my oil consumption decrease or cease all together, than maybe the older FX's should be running a thicker oil from the beginning. Maybe the 5W-30 is used more for obtaining optimal fuel economy at the expense of using the best weight of oil for the most engine protection and that is why Infiniti states in the FSM that the heavier weights are acceptable for hot weather climates.
 
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Thanks for the information on the high mileage Mobile One oil. It get hot here in Ga. during the summer, and that is when my FX burns the most oil ,up to 2 quarts between 4K mile changes.However, I do drive my FX hard and rev past 5K often, so maybe I am burning the Castrol off. In the winter my FX burns maybe 1 qt. or a little less, but I do drive hard in the winter also. I do have over 100K miles on my FX, so maybe it is time switch over to the high mileage oil. I will use the 5W-40 for a while and check the consumption, if it stop then maybe I am just burning off the 5W-30. If my FX continue to lose oil then I will consider using the high mileage oil since it suppose to help recondition valve seals.
 
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i used to always use 5w-40, never had any noticeable oil loss using it vs 5w30. (for a vk45de)
 
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