I do find an occasional wheelweight of suspicious alloy, not sure what they are, they look like they came off of a japanese car or motorcycle. They also don't have the same sound when dropped. I don't know that what they're made out of will foul a melt, but have heard of some bad ww's out there. I simply toss such weights in the trash, better to loose an ounce or two then foul up several pounds of alloy :cry:
Almost forgot to mention, I've melted down my share of oil wheelweights, and the oil has never caused a problem the alloy, just smokes and then catches fire. I had one 5 gallon bucket where it seemed the guy must have dumped a whole quart of ATF, and then individually coated the bullets. Some folks just must not like us :?