Summer Fuel Reformulation?

[C & A s Dad]

I keep very accurate records of the MPG on my Yukon XL and can calculate my avg any time. I replaced my Trueflow foam filter a few weekends ago with a CARQUEST (Wix) paper element. I left the Trueflow tube in place .I did this becasue I am running a comparison test between the two using oil analysis. I want to see for myself if the foam filter is keeping more dirt out than a good paper filter.

 

However, since I removed the foam filter my Wife has made 3 mostly hwy trips in the truck and the MPG has increased significantly. The foam filter was not dirty and I did nothing else to the truck. The previous 12 tanks with the TF foam filter averaged 18.48 and the 10 tanks before that averaged 18.61. The 3 fill ups since replacing the TF foam filter have averaged 21.56. I realize that 3 fill ups is not a good representation but I was surprised. If the mileage remains this good, obviously the paper filter will remain in place.

 

My question is does summer formulated fuel typically produce better MPG than winter fuel? I am not even sure if the fuel in the Deep South is even reformulated for winter?

[Yuzilla]

I noticed a jump in milage within the past couple of weeks. I took a road trip to Charlotte, NC two weeks ago and got 21.25 mpg. I couldn't believe it. Most of the trip was 70-75 mph. (2002 Yukon 5.3 4x4 72k). I did the same trip a couple of months ago (winter gas) and got a little over 18 mpg. I am convinced it is the gas since I haven't done anything except an oil change in 5 months.

[Mark_in_Tulsa]

It's not so much the fuel, it's the warmer air.

 

Warmer air is less dense than colder air. Your truck wants to keep an exact air to fuel ratio of like 14:1. (or something like that) So if there is more air going in because it's colder then more fuel will be added to keep the right mixture.

 

That's my simple explanation. Someone else can chime in and give a more detailed answer.

[C & A s Dad]

Mark, the warmer air may be the answer. I read an article by a guy that had routed his intakelair to come in behind the radiator, obviously much warmer air than the outside air temps. I cannot remember his MPG claims but it was significant.

 

Pat, over 21 with a 4 x 4 is great.

[DayUSeX]

man if this rad idea is true, im going to try it out and report back

[C & A s Dad]

Don't forget, the warmer air is not Horsepower friendly. Your motor likes cool air for HP and I am sure of this. I am not sure that hot air from behind the radiator will actually help Mileage.

[svensk]

You mean your getting 21mpg just on the highway, not per tank right? Don't believe anything the computer is telling you go by the fillup.

I just replaced my O2's after they were causing problems and now I'm back up to about 15.5 per tank of mixed driving. Considering it's still been cool the last week 30-mid 40's in temp.

[DayUSeX]

so for economy i should do a cai or do this wai?/

 

ON my v6 with a tune, racks, box and tools i get around 14 highwy on a GOOD day *whacks head*

[cerbomark]

Yes, summer blend will get a few more miles per gallon. Not sure when each state changes over.

[C & A s Dad]

You mean your getting 21mpg just on the highway, not per tank right? Don't believe anything the computer is telling you go by the fillup.

I just replaced my O2's after they were causing problems and now I'm back up to about 15.5 per tank of mixed driving. Considering it's still been cool the last week 30-mid 40's in temp.

 

My Yuk does not have a DIC. I am calculating mileage the old way by using miles driven divided by gallons used. I do have an Interceptor Gauge which reads MPG but it provides instant readings only and will not give averages like the factory DIC will.

 

My last fill up was on a 171 miles which consisted of 3 different round trips all in the 50 to 60 mile range. The truck began full and I refilled and could get only 7.85 gallons in the tank. The truck was filled from the same pump and sitting on level ground. This means that 171 mile fill up resulted in 21.78 MPG. Please understand I never use 1 tank as a reading and realize that a MPG reading from just one fill up is not accurate due to condtions and possibly an air bubble in the tank etc.

 

As I said in the original post, the last 20 or so tanks has given me about 18.5 MPG which comes from a mix of driving with most of it consisiting of rural trips with some highway but also a good many short trips mixed in. I have noticed the MPG to be as low as 15.5 if my Wife's driving has been mostly around town with little to no highway at all.

 

I realize this is good mileage for a truck this size and 4.10 gears. In fact some may not belive this but I have read where others are seeing similar results. I will say one other thing. My Wife is a very conservative driver, which has a great deal to do with the truck's MPG.

[jhm]

The winter blend is just regular gasoline with an oxygenator such as ethanol added to reduce emmissions. The ethanol does not have the same power potential as gasoline so you lose about 2% in fuel mileage. That is not very much. People tend to warm up their cars in the winter so while doing this they are getting 0 mpg. Also if you live in snow country, you lose a lot spinning your wheels in unplowed roads, parking lots etc. That is more the cause of reduced mileage than winter blend.

[C & A s Dad]

Fortunately for us, the snow and ice is not an issue. A really cold morning for us may be in the upper 20s so my Wife may let the truck warm up for a little while but not long.

 

I am not really even sure our fuel in the Deep South is reformulated for winter. Does anyone know this for sure?

[pwall]

Up North, 'winter' gas will reduce mpg sometimes as much as 20%. I'm sure that, as in previous posts, that warming up the vechicle, wheels spinning more, etc don't help.

As an example, I normally get 600kms out of a tank in the summer. In the winter, this is reduced to 500kms. I don't have numbers to prove this as I don't track it.

I'm sure there is a difference in winter gas here and winter gas down in South Carolina. ;)

[J.B.R.]

Up North, 'winter' gas will reduce mpg sometimes as much as 20%. I'm sure that, as in previous posts, that warming up the vechicle, wheels spinning more, etc don't help.

As an example, I normally get 600kms out of a tank in the summer. In the winter, this is reduced to 500kms. I don't have numbers to prove this as I don't track it.

I'm sure there is a difference in winter gas here and winter gas down in South Carolina. ;)

 

 

I agree with the 20% reduction in mpg for the winter. On my dodge I kept record from new. Little 3.9v6 getting 18 in summer and 14.5 in winter.

I figured the oil co. needs to increase sales in the North country, because they sell about 20% in the winter so to recope less usage they reduce or mpg by 20%. Then blame it on the additive needed for quicker evaporation.

[Bish]

No doubt at least for me winter gas drops about 2mpg. I track every tankful in a spreadsheet and I can tell you the week they change over.

 

Regarding the cold versus warm air, cold air is better for everything. Warm air is less dense and the computer adds less fuel but that same engine now produces less power and requires more work to accomplish the same task. Cold air is more dense and the computer adds fuel but your engine produces more power or energy so it is not working as hard.

 

Think of this analogy. You are driving down the highway in identical vehicles one using cold air for intake and one using warm air (theoretically). To maintain the same speed, the warm air engine will require you to depress the accelerator farther than the cold air to maintain the same speed. So even though it is injecting less gas for the given volume of air, it will require more air/fuel to keep the same power level as the cold air one.

 

Hope that explanation helps. Bottom line, colder air is always better IMO. Now if we could just get rid of winter fuel in Chicagoland.