I don't know what k-seal is, but if it is cooling system stop-leak, I would not suggest putting it in your cooling system. There are a whole array of plastic parts in your cooling system that get brittle and start to fail after 8-10 years. Stop-leak will not help crumbling plastic.
On an e36, the most common failure is the top hose nipple on the radiator. It disintegrates from the inside. It starts to leak and within a few days the nipple blows off and your cooling system evacuates within a few seconds. This typically occurs when you are en route to the airport to catch an important flight.
On an e46, a common first failure is the expansion tank. I tried to attach a photo of the failed expansion tank on my '04 325iT. It split up the outboard side. It is an 85 kB .jpg image, but this lame website rejected it as "not a valid image file" sorry.