My engine temperature is low when it's cold outside. I'll drive for 30 min, and the engine temperature will be at the quarter mark. If it's moderately cold outside, the temperature will eventually go to the middle, but if I turn on the heating, the temperature starts dropping; because of this, I don't turn on the heating to defog my windshield. The engine temperature is OK if it's not cold outside.

I was involved in an accident, and as a result, my car started leaking oil. The mechanic said my oil pan is leaking and my rear main seal is leaking. I can smell the burning oil outside my car. Could this oil leak be related to the low engine temperature?

I have a 2000 Mazda Protege.


1 Answer 1


Oil leak is unrelated. You should fix that. (:

There are various possibilities:

  • The temperature gauge is faulty or the sender that sends the gauge the temperature reading is.

Test: Block part of the front of the radiator with a piece of cardboard. This will force the system temperature to raise. Drive around for a little. Watch the gauge. Does it go to normal operating range? If not, you can start by replacing the sender. Then look into the gauge cluster. This goes from cheapest to most expensive.

  • The thermostat is stuck open.

Test: The upper radiator hose seen here next to the right of the radiator cap

2000 mazda protege engine bay

should feel warm/hot when the car warms up. If it feels cold after a while it means that the thermostat is stuck in the open position. Replacing it is fairly simple but a bit messy (due to the coolant dripping out).

See this video of the thermostat being replaced on a similar vehicle: https://www.youtube.com/watch?v=vUp70pm51dI

  • The fan is always on.

Test: Open the hood. Is the fan on? Is the A/C on? The fan should be off if the A/C is off. It will only turn on for brief periods of time with the A/C off.

  • 1
    Thanks, I'll try this out. My mechanic says fixing the rear main seal will cost $1000 because of the labor. What's the cheapest this can be done? Dec 29, 2015 at 21:14
  • It really depends on where you live. Although $1K is not unheard of. Replacing the rear seal requires removal of the transmission. That's why so expensive. Honestly, if the leak is less than half a quart ever one thousand miles then forget about it until it gets worse. Just check your oil every week and you will be OK.
    – race fever
    Dec 29, 2015 at 21:43

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