Time to check the antifreeze level in my cars so I got out the petcock turning tool I made last year. Petcocks are often too stiff to turn by hand and it's a difficult spot to get pliers onto, so I made this tool to make the job easier. A little crude but it works. Hole is to hang it on the wall so I don't loose it. I drain out about a pint of water from the bottom of the radiator, heat it up in the microwave so it is warm enough to register on my temperature graded tester.

Ralph, you have lost me. What is a temperature graded tester? What do you learn by heating your ethylene glycol - water mix? What do you do with the old drained fluid?

TH

Terry, it's the type of tester with a float in it that measures the density of the mix. You fill it up till it floats then squeeze out enough water till the float stabilizes at an indicator letter. The chart tells you what the freezing point is based on the float level and the temp of the mix. I pour the mix back in the radiator after I have tested it.
Ralph

Thanks, if the density is off you add more antifreeze or water to adjust?

TH

If the freezing point is too high and the radiator is full, you need to drain off a gallon or so and add enough antifreeze to get it where you want it, run the engine till it is well mixed, and check it again.
Ralph

Oops, time to start sniffing glue!

Cheers,
Willis

Maybe you are describing a hydrometer? Measures the specific gravity of liquids. These were used to test the strength of alcohol in antifreeze and strength of acid in batteries. In the old days you poured the solution to be tested in a tall glass cylinder and lowered the glass hydrometer into the liquid. The hydrometer would have markings on the shaft to note.

Ralph you realize they make a tool (ive had it for 20 plus years) that you just suck up some antifreeze and it instantly tells you the freeze point, no need for heating

I am going to bet this or similar, is what Ralph has. It is a temperature corrected antifreeze tester.

https://www.napaonline.com/en/p/SER771126

Scott, that is very similar to the one I have except mine has a suction tube only 2" long, so too short to suck up fluid since it doesn't fit very far into the filler. Also the minimum temperature is 40 degrees on the chart and it's colder than that today. That's why I like to warm it up a bit to get on the chart.
But how do you guys like my tool?
Ralph

There is another tool that is very accurate: a refractometer.

https://refractometer.com/hand-refractometer/

Nearer to the bottom of the list is the battery acid/antifreeze model.

Very easy to use; just put a couple drops on the lens, close the cover, and look through the eye piece. There will be a line across the view exactly at the freezing temp. No need to worry about sample temperatures.

Like a lot of tools, good ones cost more but last longer.

Gentlemen, thank you for all the posts and input. Tons of great information in them.

Good Luck,
Terry

If you have a stock petcock, you tap the other side of the knob in and it will turn with your fingers. There should be a small spring on that side.
But your tool gets your fingers away if it's hot.

Ok, I see what you are after.

Here in Northern California it rarely gets really cold. The lowest temp I remember was about 18°F. When I used to run straight water I would drain the radiator whenever it was predicted to go below 32°F.

I now have a good radiator which doesn’t leak so I use antifreeze. I think a sample of my coolant placed in a cup inside my freezer (home freezers are set to 0°F) should do the trick. If it freezes add antifreeze to the cooling system. If it doesn't freeze then pour it back into the radiator and forget about it.

There, I just saved you from having to purchase a $100+ tool! You’re welcome!

IMHO,TH

(Message edited by Thorlick on October 07, 2018)

Ralph, your tool looks like it does the job. That's what counts!

To add to Terry H's posting:
If it doesn't freeze, check ice cream in freezer--if Ice cream has melted, have refrigerator repaired. Use known working 'fridge to check your antifreeze before returning the fluid to the car. If Ice Cream has not melted, before returning fluid to car, check that said Ice Cream flavor is still good. . . adding Hot Fudge, Bananas, and whipped cream to said Ice Cream enhances the flavor checking routine.
Don't ask how I know about the melted Ice Cream. . . (Note; see "Public Service Announcement " thread)

The title of this thread made me think of something else.