Been using PAM for years and no problems. Just don't spray it with the grill lit, flares up really well.
Jim:Science says oil goes on the food, not the grate.
Some experts say you should lube the cooking grates with spray oil. This is a bad idea. The tiny droplets of aerosolized oil are highly volatile, explosive even. If they come in contact with flame, they could create a fireball and you won't need to tweeze your eyebrows for months.
Many books say to roll up a paper towel, grab it with tongs, dunk it in vegetable oil, and swab the cooking grates. Cook's Illustrated magazine says to repeat the process of oiling the grates 5 to 10 times. Might work, might not. It depends on the temp of the grates and what they are made from.
I asked the AmazingRibs.com science advisor Prof. Greg Blonder about the pros and cons of lubricating the grill grates: "Metal grill grates, even shiny clean ones, are not really smooth. Under a microscope there are numerous scratches, pits, valleys, and ridges. The compounds in food are much colder than the grates and when the two meet a bond forms between them. If you oil the grates, below the smoke point of the oil, let's say 400°F, the oil actually does coat the grating and helps release protein and fat. But if you 'keep it hot', above the smoke point, the oil cracks, smokes, and carbonizes almost instantly. The carbon and smoke don't taste good, and the dry uneven carbon layer simply makes sticking worse. Even at high temps if you brush on oil and then immediately add food, the oil and food cool the grate and if it cools enough, the oil may not burn off. But no way it creates a stable non-stick surface." In some cases the oil can actually build up and make the grates more sticky!
The best way to prevent this bond is to pat your meat dry and then put some oil on the meat rather than the metal. As you lay the oiled meat down, the oil fills the microscopic nooks and crannies in both the food and the grates and makes a relatively smooth, slippery surface. The cool food lowers the temp of the grates and will keep that burnt oil residue off the food. But you want to use an oil that has a high smoke point. Most refined cooking oils will do the job. I use an inexpensive refined olive oil which has a higher smoke point (over 450°F) than extra virgin olive oil (about 375°F). Corn oil is good (about 450°F). And believe it or not, mayonnaise is very good, especially for fish. It is mostly oil with some protein and water. Remarkably, you'll never taste it.
As the food cooks, heat causes water vapor to exit the meat where the metal is touching it because the metal transmits much more heat than the hot air around it. That's the sizzle you hear, and it continues until the surface of the food in contact with the metal dries out a bit forming grill marks. Because oil and water don't mix, this steam lifts the meat above the oil, and eventually the food lets go. If the food is sticking when you go to turn it, just leave it alone. Vapor from where the meat meets metal eventually steams the two apart.
Don't you hate it when food sticks to your grill grates? This article explains how to prevent it: keep your grill grates clean and use the right temperature for the food you're cooking. Maybe lubricate the food (not the grates) with some oil. Some fish baskets and grill toppers may also help...amazingribs.com