Why would the oil not be pumped to the heads?

On a 2000 honda odysey van when running how much oil should be pumping to the heads

What sends oil to heads on 2000 honda odysey van

Excessive crankshaft journal wear--as clearances increase, oil pressure drops. Heads are last on the oil train and the first to suffer, when oil pressure drops. It sounds like the engine needs to be pulled and rebuilt. After you rebuild or replace the engine, start using Mobil 1 SAE 5W-30 full synthetic engine oil. Change the oil and premium filter every 6,000 miles or 6 months, whichever comes first. Then, you will have a hard time wearing the engine out.