I'm very pleased and appreciate all the response and input to my problem. Galaxy, I've been interested in water/
oil cooling/heating and have seen illustrations of GM unit used on certain 'Vettes which are part of the filter boss. Red, been covering my cooler for 10 seasons with no discernable result, which led me to this t'stat. I know it works for you and others, but not my voodoo motor. Hal, your running experiences are exactly the same as mine; 210+ with combustion heat or idling in traffic on warm days, and track use. Not much any other times. I've been considering your " bypass cooler " lines for long time now; just thought t'stat would work as designed. Jim, thanks for research on Canton site. The piece is beautiful and pricey. Just the stuff I stupidly crave. We ERA guys are used to that ahem, mentality. Also, Galaxy, I use -10, as most guys do but originals were -12's. Wilf; a man after my own heart! When I got my Mocal, I Dremelled the CRAP out of that lousy casting [to use some American vernacular], 'cause it was a mess! But your advice about the "waxstat" may truly be the heart of my problem. I never was told that was replacable and I'm going to try to get one. I guess you have to be BRITISH to get the lowdown from Mocal! Also, roger about the -12 costs. Thanks to one and all . Lets stay in touch.