Thanks SD. Called my local porsche service dept and double checked on the coolant. they said 50/50 fix is fine and they said off the shelf is okay, but reading that articule, I am now a little worry. Might need to seek some more advise from good old jim.
As for tires, I totally know what you mean as my first set of S4 tires were done by the time i hit 18K (not bad), but the next set of tires I purchased (bridgestones) had a w or z rating and guarranteed 40K on the tires! They were a $175 a piece (costco price. retail would be around $205). I was really surpise to find that and did a double take on it, but I have to say, it was a good find on tires. For Prosche, I will probably look around for all-season tires in Oct. Don't want to be hybroplaining in the rainy season. if I find a z rated tires and with guarrantee mileage, i will check them out and let all of you know.