Hi all -- Just a quick question to ask if anyone has experienced or knows the cause of this. After oil changes (seen this 1-2 times now) on my 2009 Prius, I see a drop in mpg from 48 --> 45 or so. My driving doesn't change significantly, and I believe that the mpg slowly recovers over time. Has anyone else seen this? Is there a reasonable explanation? Am I having my oil changed wrong? I usually get a 5W30 regular oil from Jiffy Lube -- nothing special. I decline the fully synthetic, because the 2009 model doesn't call for it, but would this affect the mpg? (I live in Bay Area, N. CA) Thanks!
While a synthetic 0-W20 might help some, I suspect the real issue is over filling the crankcase. Many Gen 2 owners prefer a point about 3/4 of the way from low to full. Oil Overfill Question | PriusChat
thank you! I looked at the dipstick and sure enough, 1cm over the top mark. Got Jiffy Lube to drain 0.5 qt (to 3/4 between the marks), and I believe I can already see the mpg returning to normal!
