:confused: l have a 2000 ford explorer XLT (4.0 SOHC V6) and the oil pressure has been low during the start up and then pops up to normal levels after driving/idle for few minutes.

Here is the run down: 114K miles and have used synthetic oil 10-30 regularly after the 15K mile mark and always chaged the oil at about 4k average intervals. I have done an engine flush once and replace trans fluid once and one complete flush. I have not had any problems with engine performance.

I have noticed it idles irregularly lately dropping below 500 and then up again. Normally idles at about 1000 rpm and settles to about 600 when warmed up. Everything else are still factory parts except for replacements on hoses, belt, brakes, shocks/struts, rotors, plugs, filters, battery, fluids and tires.

I would recommend you use synthetic 5W-30 engine oil, especially this time of year. This should allow oil pressure to build faster. It should also help the vehicle idle better, particularly when cold. Since you are using synthetic engine oil, there should be no need for a flush--in fact, they can be detrimental. The only product I would recommend is the ester-based AutoRx product, but it is not a "flush-type" product.

Sounds like you have been doing a very good job of preventive maintenance on your engine, but you really need to change the transmission fluid and filter every 30,000 miles on Fords, if you are using ordinary Mercon V. I would recommend you use Mobil 1 Synthetic Multi-Vehicle ATF, which is Mercon V rated. If you use this product, and are able to change the fluid in the torque converter, you could safely go 50,000 miles or further, based upon used oil analysis.

You are definitely on the right track. I would also recommend you change the brake fluid with Valvoline SynPower Brake Fluid, which is HBH rated and meets all of Ford's requirements for heavy-duty ABS brake systems. Read my FAQ section on Txgreasemonkey Recommended Preventive Maintenace. You can easily do the brake fluid yourself, if you get the One-Man Brake Bleeder described. Bleed in this order: RR, LF, LR, RF.

Thanks. The temp in CA (West Covina) has been in the 40's at night and maybe even slightly colder and was also thinking of going to 5w-30 syn oil.

In regards to the trans fluid I think I changed the fluid the first time at 75k with Mercon V, added the Lucas additive, replaced the gasket and filter myself. The second trans fluid change and was at 100K (done by a goodyear service center) and a complete flush, filter and gasket replacement.

But hopefully your suggestion resolves the low oil pressure gauge issue. If not what else go it be? I hope not, since I think I have taken good care of the engine and really don't drive it hard or abuse it. I drive normal, street and highway appropriate never hard acceleration and braking or push the engire to perform hard and under harsh conditions.

Because of how well you have taken care of the engine, I can't imagine it's anything serious.

What brand of oil filter are you using? Different filters have different psig readings. I have found Motorcraft, Purolator (who makes Motorcraft for Ford), and Amsoil filters work very well in Ford products. Oil pressure builds faster and these filters have silicone anti-drain back valves, which keeps oil from draining back into the engine overnight. I use these filters on my 2000 Ford Taurus with a 3.0L Duratec Engine.

I've also replaced the brake fluids as appropriate, just can not remember the brand.

As for the oil filter I use Fram or Puralator and sometimes another brand if neither is available or out of stock.

For the syn oil I use only mobil 1

Try the Motorcraft filter, which you can get at WalMart for $3.28. It may allow your oil pressure to build faster and totally eliminate your concerns. I think you are going to observe your oil pressure building much faster with 5W-30.

My son lives in L.A. and uses Mobil 1 5W-30 EP and Mobil 1 EP filters in his car. He is not into working on cars but he has always used synthetics and it has kept him out of trouble.

Thanks, I never really gave it much thought to the performance of the oil filters.

Does price indicate better performance? I have used Motorcraft a few times, but Fram and Purolator I used frequently. I figured factory parts were also more just more expensive because of the name.

Normally, you get what you pay for. I run the premium filters in my cars and feel they are worth the money; however, I always buy them on sale.

Soooo what was the problem? Mine is doing that now

If none of the above worked?
I would change Oil and Filter, If that doesn't work, I would reread the above post, good info.

Ocala, low oil pressure is usually due to engine journal wear, not oil pump wear. The oil pump creates flow, while journal clearances create pressure. Wear increases journal clearances, causing oil pressure to drop.

I wonder if anyone ever gave any thought to a bad pressure sensor? As I have a 2000 Explorer and have experienced the exact problem described, including the idle issue.
I had a bad pressure sensor and a leaking intake gasket. Pressure sensor caused no oil pressure to show as the gauge only shows none or all with no actual pressure reading. It's either on or off on these cars.
The intake manifold produced a vacuum leak creating a "Bank 1 Lean" code which would cause the computer to inject more fuel revving the engine to 2000 rpm, then it would reduce the fuel injected to an amount that would cause the engine to die. This continued until the engine was at operating temperature.
About a 600 dollar repair at the dealer with a 1 year, 12,000 mile warranty.