You're probably right about the undefined region on the Oil Temperature gauge, but the EGT graph is different (think about it for a bit).That may be a version of black instead of gray. From page 7-80 of the SkyView System Installation Guide, Revision AL:
"If a range is not defined, it is considered black ..."
So maybe that range is not specified, like the black in the CHT/EGT gauges to the right of the green bars on those gauges in your pic.