What temperature should a small metal pot be at for testing oil for having antifreeze in it?

[JimPghPA]

The coolant over-flow bottle in my 2016 Honda CR-V has always been exactly at the low mark ever since I bought it in February of 2020 with 19,877 miles on it. Yesterday when I looked at it it only had about 1/4 of an inch of coolant in that over-flow bottle, so during the last 3 weeks it has lost about 4 or 5 ounces of coolant. I had it parked facing up hill and coolant is heavier that oil, so if there were coolant in the oil it would sit in the bottom of the oil pan, and because the oil pan drain bolt is on the bottom back of the pan that bolt is on the downhill side when the vehicle is facing up hill. I even raised the passengers front side so the back side of the pan the oil drain bolt is on would be the lowest point, and let it sit like that for an hour and a half. And the vehicle has not been started in 2 days so if there were any antifreeze in the oil it should have settled near the oil drain bolt. Then I drained 9 ounces into a glass jar with a big funnel duck-taped to the top of the jar. I did not see any antifreeze coming out the oil drain hole, and the bottom of the jar does not look any different then the rest of the oil in the jar. So I suspect there is no antifreeze in the oil.

I want to test the oil by heating a small stainless steel pan and putting about 1/2 an ounce in the pan to see if water boils off.

The oil is Honda 0W-20. From what I can find, it looks like the flash-point is 425 F.

I have an IR temperature reading gun, and a small stainless steel pan that is about the size of a cupcake, but narrower on the bottom and wider on the top. I can pre-heat this small pan with an electric stove and quickly remove it and add the oil to see if water boils off.

What I need to know is what temperature should I pre-heat the stainless steel pan to for doing this test?

And yes I do have a fire-extinguisher handy ( actually 2 of them ), though if it catches fire only in the pan I will just put the pan in a sink.

 

[JimPghPA]

Now that I think about this, I will be wearing my welding gloves, an old long sleeve winter coat, a winter hat, and a full length clear plastic face shield when I add the oil to the hot pan. I expect there is no antifreeze in the oil, and it will not splash or violently boil, but the time to put safety items on is before doing what may cause a problem. Better over-kill on the protection, than not enough.

Once while working the 3rd helper job on a blast-furnace at night in J&L steel I saw molten slag poured into a slag ladle that had sand that looked dry but still had some moisture in it sitting in the bottom of the ladle. The steam blasted 18 tons of red hot molten slag 50 feet into the air and it rained down on everything. Everyone had full silver asbestos heat suits with clear face shields on so not one was hurt, and after it subsided it took two RR engines to pull the ladle car on the track through the slag on the track. Steam can do wicked things when it launces hot liquid into the air.

 

[Dave9]

This test does not seem needed since you don't visually see any antifreeze in the oil, but if you want to do it anyway (too much free time?), at anywhere near a 50/50 mix, your coolant boiling point should be a little below 250F so that is a good target #.

No, do not pre-heat the pan to some high temp then pour cold oil in. Heat the oil in the pan while monitoring temperature. There is no way to predict how hot you would pre-heat it anyway, well someone with the right credentials could determine the thermal capacity of the vessel and of an exact amount of oil to raise n# degrees but it's not a good idea to overheat the metal then pour the oil in, that is exactly what might cause an accident where you need the protective gear.

You already stated that you believe the antifreeze will sink so why not just pour it into a glass and wait to see if it separates? Otherwise, if it doesn't look like a chocolate milkshake it is not likely that this is where you're losing coolant.

Have you examined around the water pump and radiator for coolant that might be leaking slow but boiling or drying off so you never get a puddle? Checked the ATF for contamination? IMO if the oil looks right it is the last place to continue investigating. Next, maybe pull the spark plugs and examine, do a leak down or compression test while they're out (and install new if they've got over 50K mi... might as well), see if there are bubbles in the coolant reservoir and do an exhaust gas test there.

 

[cdlamb]

If you have an internal coolant leak, the engine oil is probably high enough that it will evaporate the water off, & you will only see the ethylene glycol, or the antifreeze compound in your cooling system.
Oil analysis is probably the best way. I had a ford 4.0 rebuilt in a 1999 Ford Exploder. After it was rebuilt I sent an oil analysis away, & it came back showing unacceptable contaminant levels from antifreeze. It wasn't visible in the oil visually.

 

[FowVay]

I remember doing something like this in the kitchen during my first marriage. My wife came home and saw the motor oil on the stove and a cylinder head in the dishwasher and she hit the ceiling. I would have fared better if she'd caught me in bed with the neighbors wife.