[Modena]

I am using an "ImprovedRacing" thermostat that avoids this, here is an excerpt of their explanaion of how the unit operates;

https://www.improvedracing.com/

The way it works is there is a bypass valve in the center, that connects the two sides together. This valve is normally open when the oil is cold. Because there is more resistance for the oil to flow through the cooler and lines, over 90% of the oil simply flows through this bypass and goes back to the engine.

We do it this way instead of cutting flow off to the cooler completely because:
1. It prevents the system from being "shocked" by a sudden flow of cold oil in the cooler
2. It prevents air bubbles from accumulating in the lines or cooler
3. It allows oil in the cooler to be drained more easily.

When the oil reaches operating temperature, the valve closes the bypass, and all of the oil is now forced through the cooler.