this topic is akin to synthetic vs standard motor oil. we all have our own experiences and opinions.
not much diff then politics. we know what we know......
I had a buddy who had over 30 years of ASE experience. He sold me his taurus, which always ran hot. Told me I couldnt remove the thermo to cool it down, because the computer wouldnt let the engine run. I removed the thermo, it ran 10 degrees cooler and told him to hop in. Lets go for a ride.
sometimes thats just how it works out. Yes, running cooler may not always be better- but many times it is.
I was 30-year ASE Master mechanic, ASE Heavy Truck Master Mechanic, ASE CNG Mechanic, ASE Parts Specialist and a couple more. For one thing, any idiot can go get a study guide and go pass those tests, they do not make you a "Master Mechanic". I was also a licensed Smog Tech. I was also contractor with the State of CA, helping write the smog test questions for the smog license. The computer-controlled cars have to reach operating temperature for the computer to go into "closed loop". That is when it is taking in info from the input sensors and making adjustments to the fuel and timing. If it does not reach operating temperature, because of a stuck open or incorrect thermostat, it will set a code and turn on the light. The engine will run okay but the computer will not be fine tuning the fuel ratio based off of the oxygen sensor. An engine emits more emissions when it is "not" at the designed operating temperature and if cannot go into closed loop it will get poor fuel mileage. The kid at the parts store will ask you if you want a 160,180- or 192-degree thermostat. The catalog does not say which one was original equipment for you vehicle. If you install the 160 on a modern engine, you're going to have a check engine light and poor fuel mileage The manufacturers want the new cars running close to 200 degrees. A flathead driven on warm
We had a fleet of 400 vehicles, some of them they kept for twenty-years. I saw a lot of heating problems over the 30-years. I found way more thermostats that failed for sticking open than closed. We had a steep hill by the shop we used for road tests. If a vehicle's temp was okay driving on the flat ground but would overheat climbing that hill, it was almost a plugged radiator. If we suspected a thermostat, we would heat up water in the boss's coffee cup to see if the thermostat would open. If we were replacing the radiator, we always replace all the hoses and the thermostat. Green 50/50 coolant needs to be changed every two-years and nobody does it.
The two vehicles with cooling problems issues that kicked my butt. One was where the impeller on a new water pump was slipping. The other was an F-800 that I had diagnosed the radiator as being plugged and sent it out for a new core. They re-cored it and it still overheated. I replaced everything associated with the cooling system and it still overheated climbing the test hill. We used two different radiator venders. I was at the other shop run by an old-timer. I was dropping off another radiator and I asked him about the F-800 radiator. He said, did they use the small tube or big tube core? That was the problem. Never assume that a new part is okay. We had a lot of new thermostats that would fail to open. We always tested the new ones first in hot water with an infrared thermometer. You never know what has been done to these old cars. But you know they came from the factory "not" overheating. If you start changing the original design from the factory, you're not fixing not problem.
My dad said every summer they would tow a trailer from North Dakota to CA, across the 100-degree desert with an almost new '53 Merc and it never overheated.
