My Buick with the 3.8 has been whistling at me -- a whine on cold startup that lasts for about a minute, then vanishes as (I presume) things warm up. My regular mechanic suggested a quick squirt of WD-40 on the belts and pulleys. The 40 is nice to have around the house, but what about these belt dressing sprays? Any harm possible to modern belts? And should I spritz the belts while the engine is running? Any input welcome!