I have used this stuff in bikes (tubed) and cars (tubeless).

In the bikes I have used it for prevention on UK trails. Great for nails and barbed wire, although some pressure may still be lost. Useless for bigger holes such as pinch-punctures (caused by hitting rocks hard at low pressures). You still need a spare tube or a cleaning agent, such as isopropyl alcohol to clean the mess before applying a patch. (I carry 5ml of isopropyl regardless to clean the tube before applying patches- it goes a long way - buy a CD cleaning kit, you get the handy small bottle).

In the cars I have used it for repairing punctures that the tyre shop refuses to plug (again only in the UK), as they are too close to the edge of the tread. Works reasonably well, but only for small holes again (they often still went flat or leaked gunge during very hard use). By 'hard use' I mean you can smell the tyres being abused.

I have not used it outside Europe & would say that it is logical that higher temperatures would affect it's performance. Whether it will work reliably at 40C ambient, with a heavy load, I don't know.

Best place to buy it that I have found is any farm/agricultural supplier. 1/4 price of a bike shop.

I would recommend using the largest qty given in the range for the tyre size on the container. Remember though that you are increasing your unsprung mass & since you are carrying a pump anyway, why not wait until you get a flat, find the cause & if it is a small puncture gunge it & re-inflate.

On the other hand, if I new my punctures would be frequent and be due to thorns/nails & no pinches, or if I was on a tight schedule, then I would pre-emptively gunge.

HTH

Ian