I hope someone knows the answer to this because I have looked on the cones for a thread weight number and can't find one. Just by holding Metrosene poly thread next to Maxilock, the Maxilock looks a bit thicker. It's also not as smooth as the Metrosene, so whenever I use it on my sewing machine I use a brush to clean out the bobbin area.
I know it holds up well to frequent laundering and the stress on seams that jeans have. At most, you might have a little more fuzziness to the thread after frequent usage, but so does the expensive cotton thread on my often-washed quilt.