No butchering, but that's way too high of a change from one grade of oil. There are many, many factors that influence fuel consumption and it's impossible to correlate one minor variable to an observed change in everyday driving. Here are a couple of posts by someone that knows more than I do and he's correct about the difficulty. The second one is about gasoline but the concept is the same. I once posted an article that noted the energy density of gasoline varies up to 4% even at the same gas station, apart from winter to summer blend changes. So at this point you're into the noise without even trying.
Remember it is one thing to observe something but being able to ascribe it to a variable is the much harder part.
Your stuck on door sticker for a tire size and speed rating that no longer exists on either car… The OEM tires on the Saturn were 185/65R15 with 30 front / 26 rear, with 35 PSI max, “T“ speed rated… Current 51 PSI max, 205/60R15, “H” speed rating. Put 26 in the rear on the current tires, this...
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Get all my Premium at Sam's Club. Other places around here are 40-50 cents more expensive than Sam's Club premium, making it well worth driving a couple extra miles to fill it up. Get my 87 wherever it's convenient.
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