I had a friend who was using auto-rx on his Mitsubishi and he was complaining that his enine was sludged up and he had recently failed emmissions. We went for a ride in his car and I noticed his coolant gauge was on cold. It was quite obvious that he had a thermostat that was stuck open.
Auto-rx is heat activated, so you want your car to run at the optimal temperature. If you have a coolant temp of 195 degrees your oil temp is probably up around 200 to 210 degrees, this is important since any condensation will be burned off or vaporized.
When I started auto-rx I was running a 180 degree thermostat, now I have a 195 thermostat and I notice with the Maintenance Dose of auto-rx that when I change the oil it does come out darker. If the oil temp is too cold you can develop sludge, coolant temps and engine oil temps run together, meaning if you have a stuck open thermostat and your coolant temp is about 150 degrees or so your oil temp will not be 210 degrees, but maybe 170- degrees, this is too cold and will lead to problems.
Running a lower temp thermostat is old school since today's oil's can easily handle 210 degrees.
So, before starting auto-rx please make sure your thermostat is working properly, you can check this by popping the hood after a long drive and checking the upper radiator hose to make sure it is hot.
Auto-rx works, but you must be sure your thermostat is working properly.
Colder than normal engine temperatures will also lead to reduced gas mileage. Gas burns more efficiently the hotter it is (to a certain point, but let's not get into octanes and all the chemical stuff). This is one reason for the EGT valve, to introduce hot exhaust air into the cylinders along with the cold fuel/air charge.
If your coolant temperatures are consistently very near the Cold mark or drastically changes while driving, you should have your coolant system inspected.
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Colder than normal temps will trick the computer in your car forcing more gas and the engine will run richer.
I post about stuff like this from my observations and I hope that people reading this will learn that you cannot blame auto-rx for an engine that is not running right.
When I ran the 180 thermostat I had a little bit of sludge in the cylinder head, I observed this when I pulled the valve cover off, I have been running the 195 thermostat for 7 months and when I took the valve cover off on Sunday there was no sludge in the cylinder head.
