Alternative oil question answered

[Rico567]

We are keeping our son's '09 Hyundai Santa Fe (3.3L V-6, 2WD) while the government has sent him and his family to Japan for a couple years. The vehicle had had a dealer fill of Valvoline 5W-20 previously. Went to do the first oil change, and since the manual says that both 5W-20 or 5w30 can be used, I changed with Mobil 1 5w30, since I already use it in my truck. I did notice that only 5W-20 was stamped into the oil filler cap, but didn't think anything about it.
I experienced a significant loss in fuel economy for the first time in my life, in a variety (about 20) of vehicles that we have owned. The Hyundai experienced a solid 10-15% loss in fuel economy with the 5w30. I can't think of any reason why this should have occurred, but we drove it 3-4K before the change, and have driven over 1K since, so I'm sure the difference is real. I think it best if I switch back to 5W-20 this Spring, and stick with the primary oil for this car.

 

[bluestream]

Going from 5W20 to 5W30 would cause .6% drop in fuel economy according to Ford. In our Ford Escape fuel economy went up when I switched to 5W30. You must have another reason for the drop.

Same batch of fuel? Same outside temperature? Same humidity? Diving different route? Many variable

 

[river_rat]

Is it in 4WD?
I can never tell a difference when I go to the 30.

 

[ArtDart]

My Huyndai Accent got better mpg's
with Mobil 1 0w30 than RP 5w20

jringo

 

[spasm3]

I've run ow 30 and 5w 40 in my escape instead of 5w20, I can't see a fuel economy difference.

 

[charbaby]

Strange!
My daughter has been complaining about MPG with her '06 Mazda3 2.0L auto. This is her 2nd winter with this car and the MPG has really dropped in comparison to last winter. It really is much colder consistantly, this year than last. Winter 2009/ 2010 was more around 28-20 MPG

So, I recently(3 wks ago) changed out the 5W30(4500 miles OCI) that was in her engine(2.0L) to 5W20 and the MPG has dropped even further...Strange!

She was complaining about the 26-27 MPG that she was getting each tankfull of gas this winter 2010/2011. Now with the 5W20, it's coincidently down to 25 MPG the last several tankfulls of gas. Hmmmm! She fills up about twice a week using a varirty of stations.

Yes, she was ready for an OCI and I thought that I would be helping her to at least stay at or near the upper 20's in MPG but this was not the case!

During the summer months and even into the autumn, her MPG on 5W30 is in the lower to mid 30's MPG(33-35 MPG). This is great for this car as I am speeking of city MPG. Hwy MPG is over 40 mpg.

Actually, I have used both 5W20 and 5W30 in the summer without any change in MPG. She has gotten between 33-35 MPG on both wgts of oil(5W20 & 5W30). She fills up twice a week so there is much of data to go by here. 5W30 helps the engine remain more quiet with the same MPG as 5W20(summer).

I don't know what has happened here. Could be the extreme cold(for us) and the winter fuel, IDK!

Extreme cold to us here in Rochester and Buffalo may seem warm to others in MN, WI, ND or our friends in Canada. But, it's still cold.

 

[volvomix]

Winter gas is formulated for winter and as such will get less MPG than summer gas.

Winter driving diminishes MPG with people warming the car up. Additionally, poor weather means slower commutes, more stop and go and so on. The car idles at a higher rate with intense cold taking longer for the car to reach a proper idle.

It's not the oil. Tune the car up with new plugs, run a fuel injection cleaner through the intake or tank. Changing viscosity to another oil won't impact MPG at all. At least none that you can measure.

 

[Johnny248]

In our Kia I've run both 5w20 and 5w30, and any difference in mileage is negligible. 10-15% does not seem possible from the oil.

 

[Rico567]

Thanks for all the responses.....although I can't see any daylight with this problem yet.
In answer to some of the questions, it's been various tanks of 87 octane gas from a number of different stations. Outside temperature and humidity has been "all seasons." Most of the driving we've done with this vehicle has been on highways with the cruise set whenever possible, at 65-75 mph, so- it's been more or less constant.

I'm looking at a highway mileage that's gone from an average of 24-25 to 21-22. I believe I have enough miles on both oils to establish this variability in MPG, even though I could do more to attempt to rule out variables, like gas up at the same station all the time (not really practical on trips).

NB: As mentioned in the OP, this is a 2WD Santa Fe, and I agree with all those who said that they think this much loss in MPG from motor oil is unlikely. Nevertheless, I'm looking at a big change in indicated mileage (although I suppose that the car's trip computer, which is what I'm using, could be at fault) on a fairly late-model car with only 13XXX miles.

 

[GMorg]

For each degree Fahrenheit that the temperature drops, fuel consumption will increase 0.2% (5 degrees, 1% change in mileage). This will occur without any change in fuel formulation or driving style.

 

[spasm3]

I changed my upstream o2 sensors in the escape @130,000 miles, fuel mileage went up about 2-3mpg. I was not throwing a code either.

 

[charbaby]

Originally Posted By: volvomix
Winter gas is formulated for winter and as such will get less MPG than summer gas.

Winter driving diminishes MPG with people warming the car up. Additionally, poor weather means slower commutes, more stop and go and so on. The car idles at a higher rate with intense cold taking longer for the car to reach a proper idle.

It's not the oil. Tune the car up with new plugs, run a fuel injection cleaner through the intake or tank. Changing viscosity to another oil won't impact MPG at all. At least none that you can measure.



Yeah, I don't beleive it's the oil either. Coincedental!
Considering I changed to 5W20 from 5W30 and bumped up the tires a couple of PSI to take them to spec. No other changes, just checked all of the other fluids. Then the MPG has dropped 1 more MPG!

I realize winter time cold and longer warm-ups does lower MPG with all the factors that you[volvomix] mentioned. I have noticed though that our MPG has dropped substantialy more so over the past couple of winters even more than ever. We usually take a 4+ MPG hit in the winter months. Lately, it's been more along the lines of 6-7 MPG compared to our best measurements during warmer months. Spring and Fall have their own MPG measurements and still respectable in all of our vehicles, I must say!

Keep in mind that I have been measuring MPG in all of my vehicles over the last 35 + years or even longer. My wife thinks I'm being anal that each time I fill-up, I take out the calculator from the glove box. I've always been this way so, to say the least, I have lots of data.

Can't complain about the way any of the vehicles are starting/running. Beautiful! On the coldest morning/evenings after have been sitting all day/night, they all start right up and run well all day long.

Even despite the greater loss than what I think is normal MPG, it's a reassuring feeling to have new tires, batterys, fresh oil/filter & fluids, new wiper blades and good heat.

Hmmmm! I may have just answered my own question!

All vehicles have new(er) tires! Which may be less noticable(as-far-as MPG) in the summer or warmer months but really noticable in the winter.

 

[charbaby]

I was talking to friends/family yesterday just after I posted the above and made mention of this subject and MPG. Many of my friends/family are not diligent in measuring their MPG so, they never really know what it is at different times of the year. And since the price of fuel varies so often, it's hard for them to measure fill up cost alone from tank to tank as it varies as well.

"It's not as though I spend the same money each week when filling up from a 1/4 tank" one friend commented. "It's different each time I fill up, running between $48-$54 at 1/4 tank when only adding ~ 15.5 gallons", he said.

I also asked these folks if it has been colder this winter than other winters in the past decade(as I haven't noticed). They all said, "YES"! "It hasn't been this cold in many years", another said. "We have had consistant cold every day with few exceptions", they all agreed. "We may have had colder indivdual days in past winters but this winter has been really much colder according to the National Weather Service(NWS)", a family member commented.

So, I may have narrowed down where my fuel economy is going and since many other online firends have commented on their MPG as well this winter, I guess I can blame the cold tempuratures. I don't see it in my home heating costs(PTL) each month. The G&E seems reasonable this year considering how often my furnace has been running.

 

[Eddie]

Winter fuel results in lower mileage due to the increased volitility. Many have reported a 5-10% loss during the colder months due to fuel & thicker fluids in the engine & AT & differental.