Hi. We have a 1997 Mazda Protege, 1.5L engine which runs very well with slightly over 100,000.
Problem that has surfaced is the engine runs hot, nearly at the red line.
I drove it today and the oil temp was roughly at mid point. It was a cool, rainy day. On hot days, it rapidly goes up to the max.
Today, I observed the temperature guage vacilating between midpoint and hot. Temp guage used to be slightly below midpoint.
Fan works. Temp sending unit is connected. Coolant is at level. Engine otherwise runs very well and luckyly has never boiled over.

My question: What may be causing the fluctuations of the oil temp guage while driving, mostly going towards the hot ?

I look forward to your response.
I can do minor work on vehicles and changint a sending unit or thermostat should not be too difficult, but your assistance is sure appreciated. Thank you.

renoir911@yahoo.ca

 

Reply to my own post after fixing the repair.
It was the thermostat! Changed it and temperature guage works perfectly again.
Not a difficult fix.
It's my wife's vehicle and the engine runs well, but automatic transmission shifts hard, vibration noises are loud at certain rpms and I really do not see what she sees in this car. I'll stick to Toyota products for a much better finish and rust protection, and of course, dependability.
Good night and thank you for the responses.
R. May