Enhanced Vehicle
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- Oct 21, 2012
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Actually...is there a big difference between 5w-30 and 5w-40? Coz my car spec for 30 but it is harder to find. 40 can withstand higher temp without major changes in viscosity..shouldnt be affecting much I guess if I use 40?
Technically, you might have very big difference, or very little difference....
At 100 deg C, Viscosity of oil if falls within range of 9.3-12.5 cSt will be Xw30, if it falls within range of 12.5-16.3, it will be Xw40....
So, if you are comparing oil that is having 12.4cSt @ 100 deg C and 12.6cSt @ 100 deg C, According to SAE standard, you are comparing xW30 with xW40 but in actual technical fact, their difference is only 0.2cSt in viscosity.... hence, very little difference....
But if you are comparing oil that is having 9.4cSt @ 100 deg C and 16.2cSt @ 100 deg C, According to SAE standard, you are also comparing xW30 with xW40 but in actual technical fact, their difference is 6.8 cSt in viscosity.... hence, very huge difference....