Can oil really make this much MPG difference?

[MrWideTires]

I have been driving my SpecV soft lately (as soft as I can... it's a track prepared car, it's nearly impossible to drive it slow)... and it used to average 26mpg using GC, now I switched to Castrol Edge 5w30 and it is averaging 29mpg... today I even floored it a few times and the average is still 29mpg.

It warms up faster, and it feels smoother.. but I can hear more ticking.

 

[beast3300]

I'd imagine the "energy conserving" on the API donut helps. I never used GC so direct experience from that is null.

 

[HTSS_TR]

The average of '00 E430 was 24.xx MPG on the trips to Vegas with Mobil 1 0W40, it went to 26.xx MPG with Pennzoil Platinum 5w20. Thinner oil does get you better MPG.

 

[Quattro Pete]

Originally Posted By: beast3300
I never used GC so direct experience from that is null.

And I've used GC pretty much exclusively, so I can't compare either. But it is not unheard of for people to report a noticeable drop in mpg when using GC.

 

[Ursae_Majoris]

IIRC, GC is a thick 30, more like 40.
I can see how switching to thinner 30w might make a difference, but 3 MPG? Did you switch gas stations by any chance too?

 

[MrWideTires]

Originally Posted By: Ursae_Majoris
IIRC, GC is a thick 30, more like 40.
I can see how switching to thinner 30w might make a difference, but 3 MPG? Did you switch gas stations by any chance too?


No, I always use Shell or Chevron 93 octane.. and usually from the same two gas stations

 

[hate2work]

Did you drive the car "soft" using both oils? Or just when you went to a thinner oil?

Are you getting your mpg number with a guage, or with the math method? I trust math over a guage.

 

[MrWideTires]

Originally Posted By: hate2work

Did you drive the car "soft" using both oils? Or just when you went to a thinner oil?

Are you getting your mpg number with a guage, or with the math method? I trust math over a guage.


I drove "soft" for several tanks with both oils.

I'm getting my number from the trip computer, but it's pretty consistent

 

[javacontour]

Exactly. Too many variables.

Make it a blind survey and see how you do. Have someone put the oil in a generic container and use it for an OCI and then switch you to another oil the next OCI and you begin to take out SOME of the human element.

Most of what I've read says moving to a more energy saving oil, and we are talking from moving from say a 20W50 to a 5W30 is good for about 2 or 3% better fuel economy max.

So your oil MAY be good for 1 MPG, maybe.

Your better driving habits, I'd wager that's a much larger part of the improved fuel economy.

 

[ScoobySTeveD]

It seems to be more advantageous in a car designed for 5W20, but yes. 10% is not unheard of. Remember that Castrol 0W30 is at the high end of the 30 scale (12.1 cSt), Castrol EDGE 5W30 is kind of low (9.8 cSt.)

 

[Rand]

GC isnt energy conserving, castrol edge is about as thin as you can go and be a 30weight.

if alot of the driving was while the car was warming up I could see it being 1-2mpg.. if it was all highway.. i dont think so.

 

[HARTZSKY]

I definately saw a loss in MPG when I ran GC in my 4.7 V8. Mobil 1 0w30 yielded much better MPG overall.

 

[rclint]

I have had bad overall luck with gas mileage computer gizmos on cars. I have never met one yet accurate to within 5 miles per gallon on two consecutive tanks !! Calculate your mileage out at your next fill up, or the next one if you need to start over, then see how it comes out. I'm not saying your computer is wrong, however I don't trust them at all (that's a hard sentence to read huh LOL)

 

[Quattro Pete]

Originally Posted By: rclint
I have never met one yet accurate to within 5 miles per gallon on two consecutive tanks !!

True, they're all rather optimistic, but that's pretty bad. Mine's within 1 MPG of actual, and I have the ability to further tweak it to curb its optimism.

 

[Steve S]

Only if you let it ????

 

[Mustang2008Z]

I use Fueleconomy.gov to determine my mpg. I have seen my mileage go from 27 mpg in my Nissan to 22 mpg, in city/hwy driving mix, I think that was due to using 10% Ethanol.
Miles driven, number of gallons to fill up, and the cost to fill up can be put in on that site to determine the real miles per gallon.

In my Mustang, the computer was on-target with the fueleconomy site after I put in the numbers from miles driven, gallons used, and cost.

My overall miles per gallon have been higher than the EPA estimates on all of my vehicles, however, it is unofficial, because it is real world driving, not government sponsored testing.

 

[MrWideTires]

So yesterday I had a pretty spirited night with my SpecV.. flooring it up and down, and I got 28mpg

I think i'm liking Edge

 

[bluesubie]

Originally Posted By: ScoobySTeveD
It seems to be more advantageous in a car designed for 5W20, but yes. 10% is not unheard of. Remember that Castrol 0W30 is at the high end of the 30 scale (12.1 cSt), Castrol EDGE 5W30 is kind of low (9.8 cSt.)

+1.

It could be in the 20 grade range for its operating viscosity.

-Dennis

 

[friendly_jacek]

Originally Posted By: MrWideTires
So yesterday I had a pretty spirited night with my SpecV.. flooring it up and down, and I got 28mpg

I think i'm liking Edge


When did you change the oil and how long are the trips? The last couple of weeks were much warmer than the previous near record cold weather. There should be a MPG difference, but not 10%.