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I tried searching before posting but idk what keywords to even use so I'm sorry if this is a duplication - please feel free to post links to the right thread.

Here's the main question:
I've checked my motor oil while running (just up to temp), off but warm, and cold. Both the warm and cold readings didn't even show up on the dipstick. Testing with the x on has the motor oil about an inch above the high mark on the dip stick. My oil pressure gauge looks good for about 1 second when I turn the x on, then it shoots to the very top of the guage and stays there while driving. What's going on here?!? Is the oil high or low?

Other things going on:
I might have blown a head gasket. Two months ago my heater stopped working so we'll, checked the coolant, low, so I topped it off. Soon thereafter my motor oil pressure gauge spiked and stayed high for a week or two. Last week I noticed the heater wasn't working so well again, coolant was low, topped it off (figured there might have been air in the system) and guess what, today the motor oil pressure gauge is back to high, even higher this time than before. I drained some cold motor oil and am letting it sit to see if the oil separates from the coolant/antifreeze and confirms this - waiting for it to settle as I'm typing this. But would a blown head gasket cause the weird motor oil level readings? I have no clue what's going on there or if it's related.
All help, insight, information is much appreciated. I'm at a complete loss. 05 SE with 155k miles. Had her for 5 years and 80k miles.
 

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You have an '05, those are well known for failing oil pressure sending units. Has nothing to do with level unless you run it low, and the fact that you don't see any oil on the dipstick when you check it with the engine off tells me you are very low on oil.

Head gasket failure is pretty rare. If you do get coolant in the oil it starts looking like chocolate pudding.

First thing I would do is top off the oil and coolant. The coolant is a bit tricky as taking off the radiator cap puts an air bubble into the cooling system. If you are very low, go ahead and fill there. Final top off is only done at the clear bottle on the passenger side fender.

There is zero relationship between the oil pressure gauge (that is pressure, not level) in the dash and the cooling system.
 

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Discussion Starter #3
You have an '05, those are well known for failing oil pressure sending units. Has nothing to do with level unless you run it low, and the fact that you don't see any oil on the dipstick when you check it with the engine off tells me you are very low on oil.

Head gasket failure is pretty rare. If you do get coolant in the oil it starts looking like chocolate pudding.

First thing I would do is top off the oil and coolant. The coolant is a bit tricky as taking off the radiator cap puts an air bubble into the cooling system. If you are very low, go ahead and fill there. Final top off is only done at the clear bottle on the passenger side fender.

There is zero relationship between the oil pressure gauge (that is pressure, not level) in the dash and the cooling system.
Think you're right. The drained motor oil was pure oil, no antifreeze. (I guess I should be relieved?)
I'm going to add oil today in spite of the pressure gauge, and I've got a new pressure sending unit on its way. I'll update Saturday or Sunday.
I feel like an idiot, but it must just be a coincidence that the pressure gauge and coolant top offs have been at the same time?
 

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Yep, you should be good after replacing the sensor. Give an update when you get it done.
 
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