Mileage and 502 Rated Oil.....

[bigjohn]

For the past 5,000 miles I have been running GC in my 2009 VW Passat with the 2.0TSI.

2,000 miles ago, I ran it in to the VW dealer and got the 10K service. They poured in Castrol 5w40.

Comparing the 5k miles on GC against the 2k miles on 5w40......the 5w40 is showing better gas mileage by 2-3 mpg with nearly identical driving.

Hmmmmm........ Any ideas? I thought the 0w30 would be the better mileage oil.

 

[addyguy]

If the 5W-40 sheared down to less than the visc. of the GC, it will produce somewhat better mileage.

 

[TomYoung]

An example, perhaps, of VW knowing what will make your car run best.

 

[bigjohn]

Originally Posted By: addyguy
If the 5W-40 sheared down to less than the visc. of the GC, it will produce somewhat better mileage.



Shear below a 30wt in 2k miles? I doubt it.


Originally Posted By: TomYoung
An example, perhaps, of VW knowing what will make your car run best.


Yeah, I am not bought in to that notion. Tons of testing shows that GC is likely, a bit superior to Syntec 5w40.

 

[TTK]

Originally Posted By: BigJohn

Originally Posted By: addyguy
If the 5W-40 sheared down to less than the visc. of the GC, it will produce somewhat better mileage.



Shear below a 30wt in 2k miles? I doubt it.


Originally Posted By: TomYoung
An example, perhaps, of VW knowing what will make your car run best.


Yeah, I am not bought in to that notion. Tons of testing shows that GC is likely, a bit superior to Syntec 5w40.


That would be Syntec GC

 

[robertcope]

Could be the car is just breaking in, too. How many miles on it?

robert

 

[CATERHAM]

Yes GC does appear to be a superior product to the GP III based
Syntec 5W-40.

Zoom-Zoom has posted a series of used oil analysis of GC and the 5W-40 in his Audi S4 and the 5W-40 did indeed sheer it's viscosity to less than that of GC, not by much though.

 

[Steve S]

Oil can't make that much difference.

 

[CATERHAM]

Originally Posted By: Steve S
Oil can't make that much difference.


I agree.

Assuming the OP was getting even as much as 40 mpg, 2 mpg improvement represents 5%.
You can get up to 1 to 2 percent improvement in fuel economy per SAE grade. To get a 5% improvement represent a whopping drop in viscosity, three grades at least.

The truth of the matter is, the difference between the two oils in question, even after shearing would be a tiny fraction of 1% and impossible to measure other than through bench testing to eliminate the multitude of variables involved.

 

[Quattro Pete]

Same ambient temps and driving conditions? Are we comparing apples to apples here?

 

[Audi Junkie]

Fresh oil has fresh friction modifiers.

This is one reason why I like more frequent dino changes, where applicable.

 

[JHZR2]

We have not seen any difference from the Mobil 1 ESP 5w30 VW 504/507, as compared to FF, Schaeffer's 9000 5w-40 or the like. MPGs have been amazingly consistent.