Getting ready to change the power steering fluid for the first time in my Silverado pickup. Truck has 200,000 miles on it and the fluid has never been changed. No leaks or anything. What brand should I go with? Is the Prestone brand found at wal-mart worth a darn? Also, anyone have any idea how much fluid the power steering system holds on an '03 chevy silverado halfton? Would I be safe buying two quarts? Thanks