PP 5w20, 07 corolla 5531 miles

[glennc]

Well I'd be very curious to know. Very difficult to eliminate the variables and reliably measure such small differences. Tires, weather, changes in driving style etc are all very difficult to eliminate, and there's bound to be lots of other noise in any tracking of mileage over time.

I have had a hard time locating any objective quantitative data on differences in efficiency with oils. I know they exist, but percentages are very hard to pin down. The old Energy Conserving and Energy Conserving II specs were something like 1-2% compared to a reference oil, but the reference oil was actually of a different grade.

I'd believe a couple percent difference between a very heavy and a very light oil in a typical app. Maybe a bit more. Either way I'd love to find some actual data.

 

[dcoyne78]

Glenn,

You are correct that these differences in fuel economy due to lower viscosity oil are difficult to track due to the huge number of variables. It seems logical to me that a lower viscosity oil would result in better fuel economy, particularly in cold weather short trip driving where the engine spends a lot of time below normal operating temperature. Even if the savings were only 1 %, over 5000 miles at 40 mpg that would be $5 (if gas stays at $4/gal). In addition if you wanted to extend your oci to 10k (which might be unwise with dino, but would be fine with PP) you would save both time and money vs 5w30 dino. Just one person's opinion, I have seen few uoas as good as Bill in Utah's so I can understand why people would follow his lead.

 

[dcoyne78]

One last comment on this UOA, which is very nice, but not as good as Bill in Utah's. One important difference is that only 40 % of your driving is highway and much of it is short trips, that kind of driving is hard on an oil. Bill can correct me here if I am wrong, but I think most of his miles are highway miles, which tends to result in lower wear. Unless your driving habits change I doubt the Pennzoil 5w30 will give you better UOAs than PP 5w20. I hope you do a UOA for your current OCI, it will be interesting.