mine is like that and i think thats just the way it is. i have had some gallons slightly worse than others. maybe just different batches. it works just fine. nothing wrong with it. 500 is not like that however. the 510 i believe to be a little thicker so i comes out the bottle looking a bit lumpy. it should be smooth though. there is no chunks in it. its just a bit more of a gel. i dont think it has frozen. i go though about a gallon a month and its been like that through the summer as well. use it, it works great