The automatically recalculated route from refueling will not usually be a problem...
That has not been my experience, but it may depend on how you have created your routes.
For some Garmin GPS devices, if the via point is placed at an intersection it will shape the route the desired direction but it will not announce the via point and it also will not affect the "distance to next turn" calculation. This is a handy way to shape your routes with lots of via points (so your route goes where you want) but without having to listen to
Garmina constantly yacking in your ear, interrupting your musically enhanced bliss. So, my normal MO for creating routes (for myself) is to place the via points on intersections that I will be passing straight through, not at turns so you will hear the announced turn directions if the intersection muting doesn't work (which it doesn't always seem to).
However, the first time that the route is "recalculated" when you load the route on the GPS device it will strip out the unannounced via points. So if a second recalculate happens the route path may change rather drastically depending on how much you depended on those now missing vias.
When I create routes for people with unknown GPS devices I just place all the route shaping via points immediately
after a turn, so the turn directions announce first and then the via point is announced, and it doesn't affect the "distance to next turn" calculation too much. Sometimes, if you get the point close enough to the last turn, it is busy announcing the turn and you are past the via point before it gets a chance to announce it. However, this technique means the route is "directional," and can't be quickly reversed unless you move all those points to the other side of the intersection
