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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