* Worn Oil Pump: The most common culprit. As the pump wears, its ability to move oil decreases. When cold, thicker oil might still be pumped adequately, but once the oil thins with heat, the pump struggles to maintain pressure.
* Worn or Damaged Bearings: Main bearings (supporting the crankshaft) and connecting rod bearings (supporting the pistons) are crucial for oil pressure. Worn bearings create clearances where oil can leak past, reducing pressure in the system. This is exacerbated by heat, as the metal expands, increasing the clearances.
* Leaking Oil Seals or Gaskets: Seals around the crankshaft, camshaft, and other components can deteriorate over time. Heat can cause these seals to expand and leak, reducing oil pressure. Similarly, a leaky oil pan gasket or other gasket in the system can contribute.
* Clogged Oil Pickup Tube or Screen: The oil pickup tube in the oil pan sucks oil up to the pump. If it becomes clogged with sludge or debris, the pump won't have enough oil to circulate, leading to low pressure, especially after the oil warms and thins.
* Low Oil Level: While seemingly obvious, low oil level can dramatically affect pressure. With less oil to circulate, the pressure drops, particularly when the oil thins out with heat.
* Oil Cooler Problems: If the engine has an oil cooler, a blockage or internal leak can restrict oil flow, causing lower pressure once the oil warms and flows more freely.
* Damaged or Worn Oil Pressure Relief Valve: This valve regulates pressure. If it's stuck open or worn, it may not restrict oil flow properly, resulting in low pressure at higher temperatures.
* Incorrect Oil Viscosity: Using oil that's too thin for the engine's operating temperature can lead to pressure issues, especially when hot. Always use the oil viscosity recommended by the manufacturer.
Important Note: Low oil pressure is a serious issue that can lead to catastrophic engine damage. If you experience this, stop driving the vehicle immediately and have it diagnosed by a qualified mechanic. Continuing to drive with low oil pressure risks seizing the engine.
