This topic has been discussed many times in the past.

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Almost no difference im MPG will be detectable. Once the engine is warm the difference in 0W through 10W is nil. In theory and during warm-up (the first 3 miles or so in cold weather) the "thicker" oil will increase internal engine drag and consume more gas. But IRW (In the Real World) this is not measureable since there are _many_ other MPG factors an order of magnatude or two higher. (x10 - x100) :shock:
FYI Penzoil is now making their synthetic version in 0W-20
I've used 0W-20, 5W-30 & 10W-30 (all synthetics) wil no discernable MPG difference.
HTH!
