Yeah this is a lie, what happens is a low temp magnet (ie 175F working temp) loses some strength WHILE AT 200F
and recovers when it cools. The amount lost is about 20-30% by my observation. TOTAL loss occurs when you hit the CURIE POINT
which is much higher, around 350-400F
It's notable that GM uses cheap ceramic ring magnets in trannies near 200F, you can bet they have a working temp of just 175F, but
at least do something.
Interestingly, if you order hi temp magnets, there is a trade-off, the higher the temp rating is, kiloguass rating drops a bit,
but stays steady at the rated temperature.
While some folks had picked up lots with a magnetic oil plug, the reality is, to make a real dent, you need a lot of magnets to see a
PPMs drop in your UOA, so the best place for that is at the spin-on oil filter, in my case: 2 FilterMags, 2 bar mags inside, 4 more bar
mags outside between the FilterMags and 1 mag on the end, gives me a 50% iron drop, but then I was at 15PPMs to start with, ie, not the
high. If you have really high iron numbers and big particles, you may see a bigger percent drop, but also you have a wear issue!