I have a 2000 ford exsplorer with a v8 engine. It is the limited model with four wheel drive all of the time. I first noticed that after it rained, at start up the oil pressure gauge does not come up to normal until a few seconds of operation. Now its becoming like every time I start it up it takes a few seconds then the pressure comes up. I have been keeping up with the maintenance and I do not just want to through parts on has any one else had the same problem?

I have seen this before and there was nothing mechanically that caused it. The oil journals that move oil around the engine and to the oil pressure switch may be a little clogged, or the oil pressure switch may need replacing but if you have oil pressure and it is correct, I would not worry about it. If it get to the point that the oil gauge does not move at all, then change the oil pressure switch.

I agree with Handyman2007. Also I know you said maintenance is up to date but have checked the oil level and how many miles are on your truck. Plus the oil pressure goes down as the oil gets old!

Sludge may be developing in the engine. Start using 5W-30 full synthetic engine oil (e.g. Mobil 1 or Pennzoil Platinum). Oil pressure builds 7 times faster with synthetics, plus it will safely clean the journal passages of any sludge.