I have a 2007 4 cyl Accord-I am original owner,change oil religiously with Mobil 1 5W-20 every 6,000 miles. Car currently has 58,000 miles. On cold weather starts (since new) sounds like what I grew up calling "piston slap" and I always thought this meant excessive engine wear. Dealer says "don't worry about it" but I do. Would changing viscosity help? Any other suggestions? Thanks for your help!