oil change frequency dino vs. synthetic

i don't think the oil cleanliness affects the mpg, although, the syn might give a bit better than dino. those intervals look fine.

 

That's approx. what I do too.
Drain interval on Gen2 is 5000 miles irrespective of type.
I use synthetic. Sometime I use Mobil-1 Extended Drain so then I feel 7500 is OK.
Normally expecting better MPG as the oil is older due to thinning with gaso etc. but to be honest I have trouble seeing a change.

 

Not at all, that is exactly my practice. I'm using only full synthetic oils now.

Prior to the Toyota V6 oil sludge issue coming up in the early 2000s, the Prius oil change interval with conventional oil was 7.5K miles. This changed with the 2004 model year when the MAINT REQD light was added.

This sludge issue apparently was not an issue outside the US, so the other geo regions did not get the MAINT REQD light. Since the issue was region-specific, that might lead you to conclude that average owner maintenance practices and/or the average oil quality used were below par in the US.

 

10,000 miles minimum for Mobil 1. Easily 15,000 for Redline and or Amsoil.