So I did my first oil change at around 3000 miles with mobil 1 0w30 because i couldn't find any 0w20.
I have noticed that I have been getting less MPG.

Has anyone else with a NAH experienced this?

Attached is a spreadsheet of gas mileage since I bought the car back in June 09'

It shows before the oil change I was getting from 29-35 mpg.
After the oil change it shows 26-29 mpg.

 

Of course you will get less fuel economy using an oil with a cSt value of 11 at operating temperatures versus 8.8. It even hurts you at start-up with a cSt of 63 versus 46.

You better look at your owner's manual and follow the manufacturers recommendations - it's not like the old days when it didn't matter much. Today it is rocket surgery.

 

Are you sure there weren't any other changes? From my perspective, it seems highly unlikely you would see a 10% decrease in mpg just from that. I am not sure what the car came with but I had my oil changed and all they had was 5-30W. I had it changed around 3500 miles. For the first 3500 miles I averaged 29 mpg. The next 2000 miles I averaged 32 mpg.

 

That was the only significant change I can think of. I am going to change the oil to 0w20 next week...so will see.

 

Notice any changes? We're going to get some crappy gas mileage here because we have so many stop signs, and the lights are never timed so we can't keep a steady pace unless we are on sunset.

 

I just filled up my first full tank after changing my oil. I am not expecting a huge difference, but will see.

 

My first couple of oil changes were 5W30 instead of 0W20, and it didn't affect my mileage noticeably. Certainly less than 5% difference (probably more like 2%).

Temperature and driving conditions make a much bigger difference (sub-freezing temps give me < 30mpg, 70 deg. temps give me 40+mpg).

I'd still recommend using 0W20 when you can get it.

 

I'm getting an oil change this weekend, I had the option to buy 0W20 for $31 or $22 for 0W30. I've used both before and haven't seen a huge difference. I just wanted to make sure to have 0 weight for the cold winters here in New England

 

From the manual:

"SAE 5W-20 or 5W-30 engine oil may also be used. However, SAE 0W-20 is the best choice for optimum fuel economy and optimum starting in cold weather."

Why would you use any viscosity not recommended by the engineers at Nissan? I assume they know more about what works best - that's their job. If 0W-30 were acceptable then I would think it would be listed. Just because 0W-20 is recommended and 5W-30 is acceptable, I don't think you can come to the conclusion that 0W-30 should be on the list as well. Perhaps it works just fine - I don't know - I'm not an automotive engineer - but I wouldn't want to find out at 60,000 miles because of oil cavitation or an improper viscosity index improver that a bearing has failed.

 

My layman's understanding of the difference between 0w-20 and 0w30 is that during a cold start, the viscosity (0w) is really light and thus allows for easier cold starts and has the least resistance. But at high temps, 0w-30 will become more viscous than 0w-20 and this while providing increased coating and lubrication, may affect the efficiency of the mileage. this leads me to beleive that the recommendation of 0w-20 is based on the manufacturers deciding the viscosity of 20w oil at higher temps is good enough for this engine and possibly selected to allow for EPA estimates and real world experience mileage to stay higher. Just my opinion based on what i know.