Dear GothM940,

Hope you're well. I presume that a 87⁰C thermostat promotes fuel efficiency by keeping engine operating temperature at the level intended by Volvo's engineers. I'm inclined to respect the choices made by Volvo's engineers.

That said, if the car lives in an area where ambient temps routinely exceed 32⁰C, the 82⁰C thermostat allows coolant to start moving sooner, i.e., at a lower temperature than would an 87⁰C thermostat.

The sooner coolant starts to circulate freely, the sooner heat is removed from the engine. In an area with generally high ambient temperatures, a cooler-running engine may last longer, but perhaps at the cost of dinminished fuel efficiency. Heat degrades lubricating oil, rubber hoses, etc.

Thus, I'd likely use the 82⁰C thermostate, if the car lives in North or Central Africa, Northern Australia, the US South/Southwest, Central America, South/Southeast Asia. In the temperate zones of the Northern and Southern Hemisphere (e.g., Europe, Canada, Russia, Argentina/Chile, Southern Australia, etc.), I'd use the 87⁰C thermostat.

Hope this helps.

Yours faithfully,

Spook