Fluctuating oil pressure query

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TimDart

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My 360 was rebuilt with all good parts inc tri-metal bearings, new oil pump etc. When hot it always shows 60psi at 3,00 revs.
Recently when cruising at high speed 80-100mph the pressure drops to 55/50psi. Should I be concerned?
When parked and in neutral the psi shoots back to 60 at 3,000rpm!
At idle the presure is fine. Could these fluctuations be to do with oil viscosity? I'm using 12w 40 non synthetic oil.
 
I am new to this board and this is my first post - I recently installed 360 MOPAR Performance 320 HP crate motor and my oil pressure when engine warm up is 20 PSI at idle and 80 PSI at highway speeds (haven’t pushed it to 100 mph yet).

Paul
 
What rpm are you cruising at when your going 80-100mph? Are you using 10 or 15w-40? Never heard of 12 myself :D. I wouldn't be too concerned myself.
 
It sounds a little like a windage thing. The oil is probably getting lots of air in it. That is if you are turning anything around 3,000 ish.
 
What kind of pressure guage are you using ? Mechanical or electrical ? Ive found the aftermarket electric guages will give you whacky readings depending on the voltage of the electrical system at different engine speeds and conditions. I dont use them for that reason and only use mechanical guages for oil pressure.
 
Guys, thanks for the responses.
I'm using a mechanical guage. 3,000rpm gives me about 75-80mph (3.23 gears). I think that the windage suggestion could be right. As i said, i can run the car in my driveway at 3,000-4,000rpm and it holds steady at 60psi.
I'm using 15w40 oil (not 12w40 whoops). What oil do you guys run?
The motor is a mild tuned 360 (approx 300hp).
 
I kind of agree with windage even tho all the other ideas are good and valid. For a kwik check drop 1 qt of oil out then test drive if its windage problem then it should stabilize and then you know what ya gotta do ...LOL also make sure you haven't over filled the pan (I've seen all kinds of oil fill requirements from 3.5 to 6 qts written in mopar manuals to the web to the local parts house guides.
 
I think you're fine. I've found oils to thin slightly when driven hard. Dont worry about it unless the pressure really drops off.
 
TimDart said:
Guys, thanks for the responses.
I'm using a mechanical guage. 3,000rpm gives me about 75-80mph (3.23 gears). I think that the windage suggestion could be right. As i said, i can run the car in my driveway at 3,000-4,000rpm and it holds steady at 60psi.
I'm using 15w40 oil (not 12w40 whoops). What oil do you guys run?
The motor is a mild tuned 360 (approx 300hp).
Click to expand...

Looks like everything has been covered on not really to worry about it. But you were asking what oil, 15w-40 rotella here daily driven. Use a good filter like Wix, stray from fram. :salute:
 
Ever tried the Rotella T-syn 5w-40? Sure it is alot more expensive, but it is great in summer and well worth it, especially in cold weather. 15w-40 is too thick to be running when it's very cold. Have you ever noticed what that stuff pours like when it gets down below freezing? Winter's right around the corner...
:thumrigh:
 
Ace said:
Ever tried the Rotella T-syn 5w-40? Sure it is alot more expensive, but it is great in summer and well worth it, especially in cold weather. 15w-40 is too thick to be running when it's very cold. Have you ever noticed what that stuff pours like when it gets down below freezing? Winter's right around the corner...
:thumrigh:
Click to expand...

I might look into swapping to that myself this winter. It's vegas here, 'winter' is what we get lol. I'll have to see what the weather is like in florida (moving) before I swap here. I ran it last winter, just left it with plenty of warm-up time.
 
Well, i raced the car all morning at a local low key drag meet. The car ran a treat with good oil pressure throughout so, i'll just relax with a beer now :drinkers: cheers guys!
 
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