There is a spongy material around the bottom of the oil pan. Can anyone tell me what this is and if it is necessary to have?

 

It's to absorb the oil from the leak prone diesel.

 

Ahh...well, it is soaked with oil

 

If you wanna clean it, put it in the dishwasher, just make sure you don’t tell your wife

No, really don’t. it’s also to quiet down the, rattle crackle of the inherently more noisy diesel.

but also very good at retaining any oil spill that motor will throw at you

 

Thanks for the info. what is the best to clean it.