Evans waterless coolant

I have used Evans in 6 of my 7 vehicles, some for over a decade. I'm too cheap to put it in my 1996 minivan, plus use up the regular coolant in it. I haven't noticed the engines running hotter. I was having an overheating issue in my 1985 M-B 300D which frustrated me for years, trying many things. At one point, I drained the Evans (didn't throw away since $45/gal) and filled w/ pure water, bypassing the heater core since that is the hardest part to rid of water, plus it was summer. No difference. The temp would creep up toward the 120 C red line at very long stoplights, then drop once driving. I finally put in a new radiator (had tried another used one and flushing both) and no more problems (runs 82 C all the time now). I pried the plastic tank off the old radiator and found a thin slime of goldish perhaps metallic "mud" covering many channels. It flaked off easy, so not sure why when I had run a long stainless grill brush along the inside top that hadn't freed it. Perhaps the difference is that the new radiator has an aluminum core and old core was copper.

Anyway, no issues or difference found in using Evans, other than no worries about corrosion or need to ever change it. One son drove my 1984 M-B 300D to LA, crossing the I-5 "Grapevine" on a 110 F afternoon. He said the temperature gage hit 105 C just before the top, which is about what I recall with 50/50 coolant under severe conditions. I understand that many new car cooling designs are verified on that stretch, since climbing 4000 ft at 65 mph in 10 miles on a hot day is challenging for any design. There are many variables in engine cooling. Specific heat of the coolant is only one, and is irrelevant if the bottle-neck is another variable (more commonly the "forced convection" from radiator to air). The "tech guy" at Evans sounds like an idiot for suggesting you remove the T-stat. They used to have smart people there, but maybe were talked into hiring a brother-in-law to answer the phone.

Before fussing with coolants, I suggest a few tests. Document the dash temperature in various conditions, from cool mornings to hot afternoons, even waiting until winter if you can. If the temperature always stays at the same spot, that indicates the T-stat is controlling, so either its "setpoint" is wrong or your dash gage is wrong. Even if working, the temperature will creep up slightly when challenged because more flow is needed on a hot day, which requires the T-stat open more, which only happens at a slightly higher temperature. Google "proportional offset" in "negative feedback control" for the engineering explanation, though it is simple common-sense which escapes most hobbyists. If you see the temperature fluctuate wildly and on the high end, you know the T-stat is "pegged out" i.e. wide-open so it can't control anymore. If you see it get too cool on cold days, the T-stat is stuck open or failed. I had that in my 1996 Voyager, running cold in winter and blocking the radiator w/ cardboard increased the temperature a lot, so pulled the T-stat and found it in pieces (stirrup had popped loose, OEM T-stat).

BTW, I have seen the temp gage indicate abnormally high in my M-B cars, which is due to an air pocket being trapped around the sensor, usually right after refilling coolant, then goes away after freeway driving and adding a little more coolant to sweep out the air. I've never seen that in my Mopar engines or heard of people fuss about trapped air like the Ford guys do, but wouldn't hurt to crack the upper radiator hose until coolant dribbles out, to insure you have no trapped air, preferably with the front on ramps to elevate that location.

Another thought is if you like the idea of Evans, but don't want to pay $45/gal, you might "roll your own". Being cheap I tried that, but don't recommend. I bought pure ethylene glycol (normal green) and propylene glycol (Sierra brand, sold at Ace) and boiled them to drive any water off (most spec up to 5%), to match the Evans MSDS. Not being a total idiot, I did that on an outdoor grill, away from the house. The boiling point is ~350 F. You see a lot of boiling at first just above 220 F (using IR gun), which is likely water. Eventually, you see what is likely glycol vapor. Don't touch it since it will be very hot condensing on your hands. The first time, I thought I saw a barely visible flame above the liquid, stuck a piece of paper in and it instantly ignited (per "Fahrenheit 451" novel?). Figured done driving off any water. I kept a lid half on to keep air away. Last pass I got too aggressive on the grill and lazy. I saw it boil over and ignite violently from inside the house, burning into the rubber propane hoses before I could turn off the valve. Could have been "interesting" if the hoses had melted thru and answering questions from the Fire Dept. Not worth the about 50% savings.