Derale 25792 Fluid Control Thermostat Kit

I was disappointed once this product arrived. When the thermostat is closed it is only a partial bypass. Based on the design it appears 30-40% of the fluid will still travel to the cooler even when closed, you can see in the pictures (in the closed cold position) there is significant free area for fluid to go past the thermoset. This will minimize the benefits of the thermostat. The literature suggests it designed this way; if true, it's a dumb design. Have you ever seen a car where the thermostat stays partially open when cold? No.You can still see significant amounts of cooling on 30-40% of fluid flow, so adding this to your cooling system will have minimal benefits in accelerating warm up to the desired temperature.

This is an excellent quality product - far better and more reliable than the cheaper alternatives.If you live in a northern climate this is a must to include with your transmission cooler assembly.

Well made product and installed just like it should

I use this unit to put a thermostat in my 4R 100 transmission on my 7.3 L diesel. I also installed a 6.0 L cooler when I installed the thermostat. I have not seen my transmission temperatures go above 190 towing through the mountains of Colorado yet.

Not a well made product, the thread is tapped so shallow you might get 2-3 full turns on your fitting before it becomes to tight to continue. Leaked immediately on startup.

I was skeptical of this when I bought it but I decided to save a little bit of money and this has worked good so far. It opens at 188 deg F, and begins to circulate oil through my oil cooler. I recommend! I am pretty sure Setrab buys these from Derale and brand them as their own and charge way more. If you look at them they look IDENTICAL.

Switches oil flow when the oil gets 183 degrees.....I can't keep up with where my oil is going with the damn black hose. But it works well!

I received it quickly. Install was a piece of cake. Worked exactly as advertised exactly what I needed.