Just got my hands on the Stanley Proto JFFCC3 antifreeze tester, and here's my honest take after using it for a bit.

First off, it's super compact and lightweight – no bulky tools here! I tossed it in my glovebox without a second thought. The plastic housing feels sturdy enough, though I wouldn’t go dropping it on concrete.

Used it on my truck and my buddy’s car. Readings were consistent with what I expected for both Dex-Cool and regular ethylene glycol coolants. The temperature compensation (Fahrenheit AND Celsius!) is a nice touch when testing hot or cold systems.

BUT... the visibility sucks. The numbers are tiny, and after just a few uses, some markings started rubbing off. For the price, I expected better durability.

Also did a side-by-side test with Motorcraft pre-mix – results were way off compared to my hydrometer. Might stick to using this for quick checks rather than precise measurements.

Verdict? It works in a pinch but don’t expect lab-grade accuracy. Probably just as good as those $10 testers from the auto parts store.