[OkieSnuffBox]

Originally Posted by Flarpswitch

I only go to a station that has 'Top Tier' fuel and select Premium for my BRZ and Regular for my Ascent. Seems like most of the time I end up at Costco. Sometimes I wonder how much Regular octane fuel is left in the pump line from the previous customer pumping Regular gasoline. Hey, I want a discount for not getting 100% premium! I remember when I lived in New Mexico during the 1970s, we had issues with gasoline blended for seasonal use considering altitude (4,500' on up) and ambient temperatures that range cold or hot sometimes in the same 24 hour period. Many cars would have vaporlock problems especially when the winter blend stocks were not depleted and the temperatures went up unseasonably. I have no idea if this is a thing now, but I assume with the advent of wide spread fuel injection and computer controls, engines can better cope with environmental conditions and fuel quality.


Something I just thought of after posting was that I don't notice any variations in performance day to day on my Subaru cars, but I do notice performance issues on my RV which is on a MB Sprinter with a 3.0L V6 turbo. I avoid Bio-mass diesel like the plague, but on a recent 2,000 mile round trip from Oregon to California, I had to use Bio-Diesel of various blends and sometime unknown ratios. Keeping track and doing the math, I estimate a 12% hit on fuel economy and I suspect an increase in oil dilution. Adding to the evidence of my suspicions, the diesel generator on the RV for the first time would shut down due to overload with the A/C, DC power convertor, fridge and then the microwave doing baked potatoes. Once I was able to get a tank of #2 Diesel, the generator was full output again. This is similar to how a gas generator output is de-rated when it is switched to propane and then even less when using natural gas. Based on these observations, I would say any paranoia about the quality of gasoline is not without merit.

Comparing "Top Tier" gasoline which is available in most of the country to "Top Tier" diesel which isn't, isn't a good comparison.

https://www.toptiergas.com/gasoline-brands/

https://www.toptiergas.com/diesel-brands/