Originally Posted By: Ken2
Motorcycle riders have reported good results with Ride-On sealant. They find that it works well, and is easier to clean out than Slime when the tire needs to be replaced. My Prius Prime plug-in hybrid car doesn't have a spare tire, and I put Ride-On car formula sealant in the tires just in case. Ride-On makes various formulations for different uses. The ATV might be most suited to mowers & snow blowers.
http://www.ride-on.com/atv-and-utvs.html
I use Ride-On in my bike, found a screw stuck in it, pulled it out and it did end up completely sealing up the hole (after a couple days of slow leaks).
I use Ride-On because of the purported qualities over over sealants. My dad has used Slime on several tires in the past with good results too, those were mostly slow leaks that weren't due to a puncture. Ride-On is a little pricier than most other options though. If it were me, for a mower/blower type application, I'd buy whatever was cheaper and more available. Looking at Amazon, you can get a gallon of Slime for $20, that sounds like a steal compared to 32 oz of ATV Ride-On I paid over $20 for.
For either product, I don't think you need to remove the valve stem, just the valve core. Since a mower and blower doesn't move too fast, I would squeeze in a higher than average volume of sealant so that it can better coat the inside slowly.