Start with degreasing the engine block. This includes the valves around and under the engine.
Clean the entire oil pan so that you can get a better view of the leakage.
Now, you need to switch on your car. This will force the oil to leak and you will be able to see where the leakage is. Lay a brown paper under your car so that you can detect from where the oil is coming out from exactly.
Next step is to check the oil filter, which will be attached to the engine under from beneath.
Check if the filter is tight enough. Loose filters can cause leakages so tighten it up if this is the case.
If the filter is not the problem, check the seams of the oil pan to see if the leakage is here. If you find the leakage here, you can get tighten the bolts to stop it. However, make sure you do this in accordance with the torque settings of your car.
If tightening the bolts do not do the job, try replacing the gasket.
You also need to check the oil pan’s drain bolt. This bolt alone can be the reason of leakage. You will have to tighten or replace the bolt to stop the leakage.
If not the drain bolt, then the leakage might be coming from the oil pressure sending unit. Every vehicle will have these units located differently. You will have to check your vehicle’s manual to see where these units are placed. When found, you will have to get these units repaired if they are damaged.