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Using 0W-40 Motor Oil Instead of 5W-20
 
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Question:
Using 0W-40 Motor Oil Instead of 5W-20
I have a 2004 Honda Accord 2.4L that I recently installed 0W-40 in although Honda recommends 5W-20. With regard to engineering tolerances, I'm skeptical that there could be much difference between Mercedes, Honda, BMW, Toyota, etc. Other than a slight decrease in mileage, I would think the 0W-40 would be a better choice based on its specifications. I also installed the 0W-40 in my 2004 Subaru Outback. I would like to stay with this viscosity if recommended, otherwise I will switch back to 5W-30 for both cars. From what I have read, it seems to me the use of 5W-20 has much to do with manufacturers' meeting certain emissions numbers and has little to do with the service life of their engine design. I would think if practically all of the European car manufacturers use the 0W-40, it would also be applicable for all other automotive applications too. Thanks... Walt
-- Walter Winter, Indianapolis, IN
Answer:
In general we recommend that you follow the OEM recommended viscosity grade, especially during the warranty period. Although, we think there is very little chance that you will have any issues using Mobil1 0W-40, you should still consider the following:
  • Your vehicle was designed to operate efficiently on the 5W-20 grade and internal engine hydraulics are optimized around this viscosity grade.

  • Mobil 1 5W-20 and Mobil 1 5W-30 are ILSAC GF-5 synthetic oils, which means they will provide fuel economy and emission system protection benefits which will maximize your fuel economy and potentially extend the life of your catalytic converter/oxygen sensors.
Answer updated April 2012
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