slow air leak in front tire

[mrlmd1]

I have a slow air leak in my front tire, maybe 5 lbs. pressure every two weeks. Both my tires were replaced, with new tubes and rim strips, by the dealer, maybe 6-700 miles ago. Using soapy water and looking for bubbles. I cannot find any air leaking out anyplace - from valve, valve stem, along either side of the rim. Other than removing the front wheel, which I really don't feel like doing, and putting it in a water tank and looking for air leaking our somewhere (spokes?), anyone have any other ideas?
I find it hard to believe I have a hole or tiny puncture in the tube, there are no punctures in or anything wrong with the tire, but the air has to be leaking out somewhere - either out of the tube, the valve stem, or the valve.
Meanwhile I just check it before each ride every couple of days and fill it up with a manual air pump which takes 2 minutes, but is still a PIA.

Anyone use any tire seal goop-in-a-can stuff to squirt into the tube? That may also unbalance the tire. :??: