Nissan oil pressure problem?

Did you check the oil level? Maybe they forgot to fill it with oil or didn't fill it with enough oil. The oil pressure switch doesn't control oil pressure. It only detects.

Take it back to the shop that did the oil change. If your oil level was fine, it could be the wrong viscosity oil or a bad filter. When a Nissan is over 75K miles, we usually switch to 10W30. A bad filter is very rare, but not uheard of. Some shops will use the cheapest filters they can get their a hold of to save a few cents.

Oil pumps in Nissans don't fail very often. They usually get replaced because they leak, not because they stop pumping oil.

Assuming oil level is ok...

Best guess is a inferior/defective oil filter

specifically problems w/the internal anti-drainback valve if it even has one.

Here's what Fram (fram.com/carcare/faq.php) has to say

"Anti-Drainback Valve. Some oil filter mountings may allow oil to drain out of the filter through the oil pump when the engine is stopped. When the engine is next started, oil must refill the filter before full oil pressure reaches the engine. The anti-drainback valve, included in the filter when required, prevents oil from draining out of the filter. This anti-drainback valve is actually a rubber flap that covers the inside of the inlet holes of the filter. When the oil pump starts pumping oil, the pressure will unseat the flap. The purpose of this valve is to keep the oil filter filled at all times, so when the engine is started there will be an almost instantaneous supply of oil to the engine."

Poor second would be inferior/wrong viscosity oil.

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Oil pressure switch - doubtful and usually doesn't make any noise.

Oil pump - extremely doubtful...

EDIT

I've run Datsun L16s and L18s well over 300k using Castrol GTX 20w50 and Fram PH8As - real good combination.

Do NOT run non-detergent oil in a vehicle engine.

I'd have said it might be the pressure switch except for the rattle. Both together indicate that it isn't building up pressure properly. It's possible that the replacement oil is too thick, in fact, not too thin. It might in fact be the oil pump that's going home.

You could do with someone putting a proper pressure gauge on it to see what's actually happening. Back to the garage and insist on seeing them do the checks.

If this problem has just started since and oil and filter change. I think it's unlikely that the oil is the problem, more likely it's the filter. All oil filters incorporate a valve, it's a rubber disc and it's just visable through the ring of holes that you see where the filter screws to the engine.

You may have a filter that does not have a valve or the valve was damaged in manufacture.

Your car is fine.....the dummies where you had your oil change probably did not put the correct oil in your car.

Any import car should use only a straight 30W oil.

Not any 5w30w oils should ever be used.

And to make things worse it is still low on oil.

You can add one pint of STP OIL TREATMENT, in a blue plastic wide cap bottle...its $2 at WALL MART or any good parts store....it will increase the viscosity of the oil to a normal level. Then next time you change oil.....bring your own oil and stand there and watch them put it in.

The oil they probably used is a Pennzoil 5w-30w its sold in bulk to oil change franchises in 55 gal. drums and there cost is about .45 cents a quart. And its over priced at that.

The STP is great stuff it will keep your oil clean and clear, and will reduce ware. Been using it a long time...even in new cars. In super hot areas in the summer it almost a must, with todays freeway temps and air-conditioners with a lot of very slow traffic.

I personally don't let any of these guys in the oil change shops get close to my cars......I learned my lesson on my favorite truck years ago.....

These shops should be regulated...they cause too much damage to cars and expense to the owners.

Well $2 will correct the problem and protect your car, but stay away from those shops unless you stand with-in 5 feet of your car while your there. If you walk away, they will do the same thing and steal your expensive oil.

30w in a Conoco, Valvoline, or Quaker state are non-detergent straight oils for cars....I won't allow Pennzoil on the property......It's a G. Bush and Joe Kennedy company, clowns like that. (see Kenzoil brand 40's and 50's = Kennedy-oil-company...then Pennzoil in the 1960's)

Your car is fine.......those guys thru you a curve....but its easy to correct......choke up the 2 bucks before something really happens to the motor.

(Houston)

More than likely it's the oil filter that is draining back

change it for the correct filter

and your problem should be solved

The big end bearing are probably worn and oil drains away from them overnight and takes its time to build up in the mourning's hence the tappet rattle

If th pressure isn't building up as fast, it could be too thin, or your pump could be going out. I'd look at the pump right away, just to be safe. Don't want to throw a rod.

i would say your oil filter

u may need a valve job