Better FE with 10-30 than 5w-30

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Guys, I wouldn't have believed it unless I just saw it unfold and and bloom this past few weeks. I'm on (and been using 5w weight to the exclusion of 10w FOREVER) a 5w-30 fill and getting no better then about 17.xx mpg. Ever since I topped off with 10-30 PYB, that mileage has creeped up to about 19.1 mpg! This is with only using 1 quart of PYB 10-30. Original fill was 5w-30 Val full syn. I am sold on this 10-30 weight now for S to SE texas and I hope to turn the corner with my oil performance(s) knowing that 10-30 is the right VISCOSITY for S (SE) texas and not the 5w-xx [censored] the car manufacturers have been throwing at us for decade(s) now! Now granted the PB may have also had the right additive pack that this Lex/Toy responds optimally and ideally but never thought 10w wold increase my FE. I was under the impression that I had to go lower viscosity on the cold side to achieve better FE but now I realize the folly of my way was not understanding that lower cold viscosity or "thinner" oil doesn't "automatically" increase FE. This may have been self-explanatory to all but I was not aware that if you get no cold temps AT ALL, you should stay away from 5ws and 0ws completely, just was never clearly explained. Was I so clearly deluded and easily misled by the oil cap and the car's manual and not on my research here at BITOG, why yes. I should have known Rule #1 and that is climate and duty cycle dictate the oil viscosity weight and not what the manuf says as a blanket rule for ALL climates and this should be considered first in the correct logical order of choosing oil. Viscosity per your climate and the heck with what the manuf calls for whether its for CAFE or simply because most cars toil in moderate to mild temps with cold being the extreme not HEAT.
 
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Originally Posted By: 901Memphis
It's not the viscosity it's the additives,try a whole fill of PYB 5w30 before you make any decisions


Wow, this is a game changer as far as additives versus viscosity because it is the additive pack indeed!! could I get better FE with 5w-30 or should I stick with 10-30 because of how well my engine (and climate) like/need it as well as PYB additive pack consisting of moly?! Chances are the 5w is not going to save me more FE or gas mileage aka miles of smiles but the add pack and TBN is a good match for this Lex/Toy! Isn't it 10-30 *over* 5w because I am in Texas and it is warm to hot *and* humid and not the milder year round temps of KenTUCKy? I learned that 5w and 0w are for those climates that get a real winter not this S(SE) texas stuff where there is only 2 seasons and that is summer and mild summer!!
 
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You saw an 11% increase in fuel economy due to topping off 1 qt of oil. Over how many miles did you see this increase?
 
Originally Posted By: Leo99
You saw an 11% increase in fuel economy due to topping off 1 qt of oil. Over how many miles did you see this increase?


This. Did you figure mileage yourself or use vehicle computer?
 
The accuracy of your test is no good. Even if you ran a full oci of 5w30 vs 10w30, it still would be hard to say its a legit test unless temps were the same and you drove exact same way. Too many variables to consider. Run a 5k oci on 5w30 vs 10w30, i highly doubt a quart of another product would improve or have that much impact on FE.
 
It's a fluke.

You need to monitor MPG for several OCI's with similar driving condition(such that you would have similar MPH), you will see that MPG is about the same for similar weight of the same or different bands(5W30 vs 10W30 vs 0W30).

Now, if you have average several OCI's MPG with xW40 you will see 2-5% improvement with xW20.
 
To back up that claim, several runs with each viscosity need to be done, with UOAs to establish trends on metals. Fuel economy needs to be logged by hand, onboard displays are not accurate enough for testing.
 
Sorry, but this is impossible. Either something else changed on your vehicle to improve the fuel economy, or your calculations are incorrect.
 
Have you resetted the computer? Mine gets better mileage in the begining of the first tank, as compared to several tank fill runs
 
Originally Posted By: Inspecktor
To back up that claim, several runs with each viscosity need to be done, with UOAs to establish trends on metals. Fuel economy needs to be logged by hand, onboard displays are not accurate enough for testing.


What do the UOAs do?
 
Originally Posted By: 06VtecV6
Originally Posted By: 901Memphis
It's not the viscosity it's the additives,try a whole fill of PYB 5w30 before you make any decisions


Wow, this is a game changer as far as additives versus viscosity because it is the additive pack indeed!! could I get better FE with 5w-30 or should I stick with 10-30 because of how well my engine (and climate) like/need it as well as PYB additive pack consisting of moly?! Chances are the 5w is not going to save me more FE or gas mileage aka miles of smiles but the add pack and TBN is a good match for this Lex/Toy! Isn't it 10-30 *over* 5w because I am in Texas and it is warm to hot *and* humid and not the milder year round temps of KenTUCKy? I learned that 5w and 0w are for those climates that get a real winter not this S(SE) texas stuff where there is only 2 seasons and that is summer and mild summer!!


There are SO many variables in real world fuel economy testing that it is just about impossible to do. Seriously. You can try as hard as you want but there are just too many variables and too many things that you cannot control. It is hard to even repeat fuel economy testing on the EPA test on emission rolls inside a building where there is no wind and the temperature, humidity, barometric pressure, etc. is all controlled. For the kind of difference you would be looking for with something like acetone in the fuel it is pointless to even consider real world fuel economy testing. You just cannot find it.
 
Milder temps the affect of 5w- vs 10w- is reduced during the warm up period. 10w- will have fewer viscosity improvers, even none with some synthetics. There should be 0 difference in fuel economy once the oil is up to temp, which in my experience is after about 15 mins of driving even in cold temps.
 
In south Texas you would need a 5w30 never. However the 2mpg from 1 cst thinner oil is impossible.
 
I like good discussions about gas mileage and I have found a "secret" way of improving gas mileage no matter what the circumstance. If you just think that you will obtain better gas mileage, for whatever reason, you will find that it is true. Try it and find out for yourself. Wash your car, polish the engine, change the oil or put cow magnets on the fuel line. You just have to increase your level of awareness. This is the reason so many products and devices are sold to increase gas mileage and the encouraging thing is that they all work to some extent.
Happy motoring.
 
Originally Posted By: hummdrumm
Originally Posted By: Leo99
You saw an 11% increase in fuel economy due to topping off 1 qt of oil. Over how many miles did you see this increase?


This. Did you figure mileage yourself or use vehicle computer?


no I HAND-calculated it.. 350 miles on 17.9, you can do the math yourself!! It's 19.x. This car neve aw above 18.0 TOPS. This is ridiculoso and can't wait to hash out more research on this new major milestone dilemma I am facing: Does the Valvoline 5w-30 original fill *in conjunction with* the 1qt, BOTH in tandem, are making the THE BIG DIFFERENCE or is it just the 1qt of 10w PYB that serves as the mother load difference maker in this equation. as we were, gents..
 
Originally Posted By: HTSS_TR
It's a fluke.
Agreed! One UOA and one tank of gasoline do not a standard make. Do this for 5 to 10 OCIs and see where you stand and even then this would not be a controlled test, but a best effort.
 
Originally Posted By: Dyusik
In south Texas you would need a 5w30 never. However the 2mpg from 1 cst thinner oil is impossible.



Originally Posted By: 2015_PSD
Originally Posted By: HTSS_TR
It's a fluke.
Agreed! One UOA and one tank of gasoline do not a standard make. Do this for 5 to 10 OCIs and see where you stand and even then this would not be a controlled test, but a best effort.


Originally Posted By: Mr Nice
Yep. Too many variables to prove correct gas mileage.


Agreed with all the above. One tankful is not enough to come to ANY conclusion.
 
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