Thanks to Bowsfixer and Laundrylady for resurrecting this zombie thread.
Why? Because I was trying to remember just when I adjusted the valve preload on my '67 Chevy Van. I guess I could always consult the service log I keep on all my vehicles, but ... there is my post up there, from 2011, telling the story. Yay.
More recently, I had cause to have to service the air cleaner housing on the van V8 motor. But that's another story.
And my advice about STPP still is good. The one thing that occurred to me now, if STPP is so good, why not add it to radiators? The reason is simple: STPP, for all its usefulness in a washer, is unstable, and would deteriorate into plain Sodium Phosphate rather rapidly in a hot radiator. It works just fine in a washer, where it spends itself latching onto hard water minerals and keeping them in solution so they can be flushed away. But in a car radiator the STPP would soon be inactivated and instead of preventing hard water mineral deposits, actually could form them.
It may help to think of STPP as a high energy chemical compound. It spends that energy by bonding to minerals and keeping in solution in a "complex". In storage, over time, STPP will release that energy and degrade into a simple, not complex, phosphate. We know this simple phosphate as TSP: Tri-sodium phosphate, which is often used to prep surfaces before painting. It's ok for cleaning walls before painting, because it won't stick to hard surfaces. But for fabrics etc it might cause a whitish residue which is the result of it bonding to hard water minerals and falling out of solution as a precipitate, which can look like lint on fabrics.
OK, enough of that.
PS-I actually have a Miele 1918 in my workshop, along with a couple of older 200F Mieles. I used the 1918 sparingly, mostly for whites. But I've got lazier for the past few years and have switched to using the Maytag Neptune for whites instead. Maybe one of these days I'll fire up the 1918 again, just for old times sake (and to get some stubborn stains out of white dish/hand towels that won't go away any other way, save chlorine bleach, which I refuse to use on fabrics).