Low oil pressure light comes on when engine is cold started in the winter time. After engine warms up the light goes out. Light never comes on in warmer weather, only winter when temperature is down to 40’s or below.
Oil level stays normal and vehicle doesn’t use any oil between oil changes. Low oil pressure light has been coming on for the last 3 winters.
Vehicle is a 2001 model with 48,000 miles.
Bad oil pressure sensor?
What weight oil are you using?
The light should come on and go right off. I mean in less than a second it goes off. I’m thinking what Beowulff is thinking here. Do you change to a lesser weight for cold months? Check your owners manual for recommendations.
Maybe. It’s properly called an oil pressure sending unit or an oil pressure switch (sensors are inputs to the onboard computer). With the symptom as described, though, that’s not the most likely thing.
The first thing to do, as mentioned, is review the viscosity of the oil being used (e.g. 5W30) compared to the manufacturer’s recommendation. In this case, the cold rating (e.g. 5W, 10W, etc.) is most relevant. If the engine has 10W30 (or 20W50, horrors!) where 5W30 is called for, that could very well be the problem.
If the oil is right, often replacing the sending unit is the cheapest thing to try next.
To know for sure whether the problem is actually a matter of low pressure, or alternatively a faulty gauge reading, the pressure can be tested with a mechanical gauge.
Your oil pressure should be highest when cold. Yes, you could have a bad pressure switch, but this happening consistently points elsewhere.
If you have a clogged oil filter, this can happen. It’s been three years so I assume you have changed filters in that time. Are they the correct filters? Double check that. The next thing to consider is the oil pressure relief valve that is designed to limit oil pressure. If the valve is stuck open, you get low pressure. This could mean you actually do have low oil pressure when cold. The result will be more engine wear at these low pressure periods. If the pressure were actually zero, you would hear noisy engine parts. Chances are the red light comes on when pressure is low, but not zero, and you would not hear engine noise without a highly trained ear and experience.
It’s up to you how seriously you want to pursue this symptom. A pressure gauge could be hooked up to the engine and left over night for a cold start in the morning. If the pressure tests low in conjunction with the red light, that relief valve is likely bad. This is a very inexpensive test and could save your engine.
The difference between winter when you have the problem and summer when you don’t is the viscosity of the oil. Most 2001 cars call for a 5W-30 or 5W-20 year around. Either one will be thicker in the winter. As Al Bundy pointed out, oil pressure is high when cold, but the flow may be diverted out the relief valve. Even with the higher pressure, you may not be getting enough flow to the sensor to open the contacts. Since the thing works fine in the summer with lower viscosity oil, I would go to a lower viscosity oil. If I may be permitted a little convert zeal, I am now running Mobil 1 0w-30 year around in both my car and truck. They call for 5W-30 and 10W-30. Even the 0W-30 is still thicker at 72 F than it is at the 200-250 operating temperature. A lower W oil should fix your problem.
I use the oil specified in my owners manual… 5W30.
The oil and correct filter has been changed couple times since problem first appeared.
The engine has no noise that would come from insufficient lubrication.
I’ll check the oil pressure with a gauge. I feel the oil pressure switch is probably faulty.
Thanks to all.