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Discussion Starter #1
I have a 67 289. Sitting for years, runs fine, did 2 oil and filter changes to clean up whatever we can. Stock gauges, seem to work.

Problem: oil pressure seems fine at idle , its higher when cold, lower when wamed up. but when we drive on the highway it goes down alomost out of the normal range. put the car in neutral and oil pressure come back up.
 

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has been stated a million times, never trust/rely on factory gauge! get an aftermarket mechanical gauge to see what the engine is really doing.
 

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Yea mine does the same... cold start and low rpm it sits 3/4 and when its fully up to temp like 1/3. Its all good... as long as u got 30-40 lbs ur fine if on a high mileage engine. One good thing is when ur pressure gets too low our lifters will make plenty of noise...

Sent from my Galaxy Nexus
 

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Discussion Starter #5
So what everyone seems to be saying is that there is never situation when this car will gradually loose oil pressure at highway speeds and then gradually recover the pressure when sitting at a stoplight.
OR,
The data from the guages is not good.
 

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So what everyone seems to be saying is that there is never situation when this car will gradually loose oil pressure at highway speeds and then gradually recover the pressure when sitting at a stoplight.
OR,
The data from the guages is not good.
Hi, First, the norm for oil pressure, as seen through the eyes of your gauge, is .....when cold, the pressure will be high(er), as the engine warms and the oil is heated the viscosity is reduced (normal occurrence) and the pressure drops.....to a point, then levels depending on engine RPMs. A healthy engine's oil pressure should be about 10 lbs. per 1000 RPMs. At highway speeds, 30-45 lbs. would be normal. At idle, it could drop to 20 lb.(?) depending on wear factors. As was mentioned, install a mechanical gauge, get a reading at idle, then gradually increase the Rs to 3K. Note the reading. Obviously, your oil level should be at the proper level. Factory gauges and their senders are not known to be 100% reliable. I think most folks, would replace the sender first. Then opt for the mechanical gauge, if still unsure. Report your findings. Good Luck!
 

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Discussion Starter #7
Problem solved. Loose conection at the oil pressure sender. Gauge readings are "normal" now. Thanks for the help.
 
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