Derale 15719 Fluid Control Thermostat Kit

Item went in between my engine oil cooler and engine. Engine oil steadily goes up to 180 and stays there. I was skeptical of this item, but it has worked flawlessly for my sbc 350 oil cooler setup.

The add says that I t comes with brass fittings, it comes with 1/2” NPT to 1/2” BARB plastic. I’m not going to use plastic fittings on my 4L80E transmission. I have around $3000.00 and I refuse to use plastic fittings. I ordered BRASS Fittings. Some people think cool fluid is the best way to go. Transmission fluid is meant to be warm and some people even eliminate the stock cooler and the transmission runs cold. Transmissions need to run 200° easy. I’m using it on my 1997 GMC Sonoma and I don’t want the transmission to be too cool. Some people think the cooler the better but I’m not one of them.

I installed this on a Rotax 9 series engine and after testing found that it was opening at 155F NOT the advertised 180F... My issue is low oil temperatures and long warm up times to get to the minimum 120F operating temp. I wouldn't recommend this product for Rotax 9 series installations.

Used this in place of the thermostatic bypass in my oil filter sandwich adapter. Working well so far. No trouble with leaks at the fittings, used ptfe paste on the threads.

exactly how described and expected

Normally, I would give the Derale oil thermostat 5 stars since I have used them for over 30 years on high end engines in trucks, cars, and planes (and a few helicopters). No, they're NOT FAA certified, but I used them since I trust them to always work as designed (with a few motor-head tweaks). Since I have about five of them laying around, I can see that the older units are better made. The castings are cleaner and the NPT threading is much cleaner on Derale thermostats from 5-10 years ago. I actually had a new one leak at the threads recently. A first. It was because of poorly cut port threads.

Used one of these in line on my performance engine in my Volkswagen Beetle. Now the oil gets to temp before it goes to the external oil cooler.

I installed is as part of an auxiliary transmission cooler. It appeared to open and close as designed and kep good flow. The only recommendation I have is to not use the barbed hose fitting and instead use AN fitting to ensure no leaks.