It is an exceptional high-temp (HT) silicon-based sealer for a variety of surface types that never hardens. It has a very friendly working time. It can often be applied to only one mating surface and needs no setup time prior to assembly. It can be put into use immediately upon application/assembly in most instances including short blocks and cylinder gasket deletes. An application can even ocassionally be reused under certain circumstances where disassembly/reassembly is required. It is fuel/oil resistant. Has an almost indefinite shelf life by simply applying a glob of Vaseline in the cap for storage -- (which works for many types of sealants, btw). I'm going on a couple years with my current 90g tube.
It became known as a Stihl product (which it isn't) due to their extensive use of it and reference/recommendation in many of their products -- particularly for their clamshell engines. The brand wars crowd seems to turn their noses up at it for that reason alone, even though it's actually made by Elring, another German company, and has been used in the Euro auto industry for decades. It was also thought to be excessively pricey as a Stihl product -- which everything is from them -- though it retails for about the same price as the other popular choices.
My favorite sealer as well. Highly recommended.
