I presume your sister has a "regular" Civic with the R18 engine. The hybrids have always specified 0w20. The R18 engine itself is the same as the 2006-2011 cars which spec conventional 5w20. Honda has stated publicly that they changed the oil recommendation for two reasons 1-slight improvement in fuel economy and 2-greater availability of 0w20 oil in the marketplace. The engine will be fine on conventional 5w20 for ~5,000 mile oil changes, but the "Maintence Minder" system may have been re-programmed for 2012 to take advantage of the longer drain intervals synthetic 0w20 is capable of.
My 2011 Civic sees usage I would characterize as "extra-urban" with very few truly short trips, and the maintenance minder recommends ~6,500 mile changes for me on conventional 5w20. Owners with Hondas which require 0w20 have reported their maintenance minders allow ~10k mi between oil changes. There are BITOG members with Fits, Accords and IIRC a Pilot which have reported such intervals.
I'll echo the sentiments of others. While there would be nothing technically wrong with using conventional 5w20 for 5k mi OCIs, the savings in oil cost is pretty minimal compared to the risk of having a warranty repair denied due to using the wrong oil. Again, there's nothing wrong with the oil, but deviating from the owner's manual recommendations may give the dealer just the excuse they need to deny warranty coverage in the event of an engine problem.
Stick to the 0w20. M1 AFE is available for ~$5.50/qt and so is the Honda syhthetic blend. It's not like they're recommending $11/qt Redline oil or anything.