low oil pressure(zero when hot)300e?+3 on Highway though

[petaling]

Problem 5 months.Not new.No castrophe yet.Does this fact alone says that there is oil pressure but not registering?????

Low pressure getting lower and lower to zero now.

Morning start-up after 1-2 sec Max pressure.
As engine heats up,gradually idles at zero pressure.No increase in oil comsumption,just 1 litre per 3-6 months as before.NO massive oil leak.

I've read that it would be the sending unit,oil pressure relief valve,main bearing ,oil pump.(the last two meaning big money)

My moonlighting MB mechanic told me as long as there is pressure when you accelerate and the needle goes up,dont worry.Just drive it.Dont spend money.

Any advice as what the cause maybe or anything that small amount of money to fix this.
Anything approaching 1000$ would mean a trade-in for me.Should i change the sending unit as a diagnostic test as I dont have tools to do pressure test etc.
Thanks in advance.

[petaling]

already changed oil to 10-40 castrol gtx and filterx1(mahle) no difference

[carymcooper]

I would try the sending unit - don't know without looking it up if there's a way to test instead of just replacing.

Another possibility is to buy a cheap mechanical gage and install it temporarily - again, I don't know without looking it up where the sender is located and how easy this would be to do.

My only other experience with this was with a Ford 351 years ago where the pickup screen got glazed over and blocked, but the pesssure was "0" always with that problem.

[petaling]

today went to Chevy dealership,this guy wanted desperate to sell me a minivan.Phoned around few wholesale places,with a/c out,evap? all said car worth 3000$ Canadian/2500 US aas trade in.He will try some more and phone me back.
Definitely a case for driving it to the ground no matter what.
Bye bye new car.
But on the other hand,may see whether MB will pay me anything more.They have a promotion this saturday,mid town.