Well guys, I set out this morning on an "almost 500 mile" day, thinking perhaps I might generate an interesting datum point or two. Boy, was I ever right! I frequently have to travel from Pensacola to Tallahassee, roughly 200 miles, depending upon the exact start and end points. Three weeks ago, I did the trip, when my Camry hybrid had a fill of 12 cSt green GC in the crank case. The engine had behaved nicely enough with the GC, but mileage was beginning to be a concern. On that trip, the best I could coax from the ECU's data display was 32.9 mpgs. Most of this trip is on I-10, with various side trips for rest, mission accomplishment, etc. Today, I did the same trip, under very similar circumstances. Same speeds, same (pig-headed) driving habits, same brand of gas (Shell 87), and so forth. The notable differences were that it was very slightly cooler (averaging in the high-80s instead of the low-90s), and it rained several times on this trip, very hard, but that usually HURTS the mpg result. And THE BIG DIFFERENCE: two nights ago, I replaced the GC with a fill of ~8.5 cSt PP 0w-20. Yes, it's true -- I changed oil myself on a Tuesday evening. After finding out I'd have to make this trip, I changed slightly early so as to avoid running over OCI because of other commitments. And yes, I have a sample of the GC to send off, and a blotter card (looks good) which I'll post later. Well, here's a very poor photo I snapped with my Canon G10 while driving down I-10W, while controlling the car, and being amazed with what I was seeing: So, what do all of you "20wt really doesn't make a mileage difference" crowd think? Alas, it will be about 1.5 months before I can sample this fill meaningfully (I will pull it at the same mileage as the GC I just dumped). Subjective observations: in motion, the PP runs just fine. No bad noises, and the car revvs up noticeably quicker than it did with the GC. I've had a couple "cold" starts that sounded a tad "rougher" than with the GC, but beyond that, all the subjective observations favor the 20 wt oil. Allright now, ready to have some fun with this?