I just tried some Victor brand stuff that is about the same as Slime.
It was easier to get into the inner-tube and it is a lot cheaper.
I got it in the automotive section at Walmart. It was $4.50 for 16 ounces. That is about 1/4 the price of Slime.
My rear tire had a slow leak that made the tire go flat in about 20 minutes. I put this stuff in at lunch today. Now, five hours later, the tires are still holding the air I put in at noon.
Despite my complaints about Slime, I figured it was worth a try rather than going through the head-ache of taking the tire off, changing the tube, and remounting.
So far, so good. I will let you know how it progresses.