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      04-24-2017, 09:53 AM   #25
bNks334's Avatar

Drives: '11 135i (N55)
Join Date: May 2014
Location: New York

iTrader: (1)

Originally Posted by Hops128i View Post
I don't understand the thermostat. I don't see any connection from the car to the thermostat? It just works all on it's own, opening at some set temperature?
Thermostats are a very basic thing. There is a rod that covers the oil passages when the oil is cold. As the oil warms up, the spring that holds the rod in place changes properties and pushes the rod away from blocking the oil passages. Oil is then free to flow through to the oil cooler. This mechanical operation does not require any electrical connections.

The stock spring and piston, sourced from a ton of difference cars, all appear to operate betweeen 230-250f. That's the oil range my 135i operates in. Anything over 255f or so and I've exceeded the stock oil coolers ability to shed heat from the oil or the radiators ability to shed heat. Either way, if your 128i is running over 250f oil, it's time for an upgrade.

Last edited by bNks334; 04-24-2017 at 10:02 AM..