88-5.0 when i first start it up the pressure reads 50psi. As it warms up the pressure starts to drop. well running at 55mph the pressure will only read 25 psi. when stopped at a idle in gear the pressure drops to 5psi. out of gear at idle it will jump to 10. i run 10w50 and just changed the oil and filter. what would cause this. any advice would help. thanks.
loseing oil pressure
- Thread starter redeye4u
- Start date
What are your revs at 55 mph (I would be at about 1K rpm with 2.73's in 5th).
Where do you get 10W-50? Is it synthetic or dino oil?
What type of gauge are you using?
Did it do this before the oil and filter change?
Good luck.
Where do you get 10W-50? Is it synthetic or dino oil?
What type of gauge are you using?
Did it do this before the oil and filter change?
Good luck.
Oil pressure dropping as the motor warms up is nothing out of the ordinary however 5 psi at idle is fairly low. I would seriously look into perhaps a little better filter if you are running a cheap(fram, motomaster, etc.). Before I became wise I used to run motomaster, identical to fram, and my OP went all the way down to 10 and idle, changed to a better filter...never drops below 25.
srothfuss
Last night I stabbed the same guy 7 times in a row
Motor could just be getting old... As the mileage increases on your car, the clearances will tend to open up and cause you to lose oil pressure. My guess is that your getting close to time for a rebuild on your shortblock.
i do run a fram oil filter. have for years. the oil is a wal mart special. but i have never had a problem with fram filters. the oil is new. the oil pressure just sarted to drop this year with the same gauge. evan before the oil change. I have the gut feeling the bearings and pump are starting to go. the motor has 130000 on it. could i get away with just throughing bearings in it and a new pump.
crazypete
All my crevices are greased.
If pressure were dropping to the point where it was affecting lubrication at idle, it would cause a lopey and rough idle. Run some seafoam through your crankcase and see what happens. 10W-50 is not good. There is too much seperation (anything over 30 weight seperation is bad) between cold/warm viscosities. Thats what bob the oil guy says 
Plus, those oil pressure sending units on the side of the block get lazy after about 100000 miles and dont send good data anymore.
I wouldnt worry TOO much. Flush the motor and yeah, ditch the fram POS for anything else. It the pressure is still low but it idles fine then chances are the sending unit is getting old and clogged. Mine dips pretty low too with 10w-30 synthetic.
Plus, those oil pressure sending units on the side of the block get lazy after about 100000 miles and dont send good data anymore.
I wouldnt worry TOO much. Flush the motor and yeah, ditch the fram POS for anything else. It the pressure is still low but it idles fine then chances are the sending unit is getting old and clogged. Mine dips pretty low too with 10w-30 synthetic.
Motorcraft FL1A is the best filter for the buck (it appears to be a mix of Purolator's top two filters).
With regard to the 30 point viscosity spread stuff: what is being talked about has to do with shear down from the heavy Gp VI and VII add packs. What I think you are specifically recalling is dino 10W-40 from back in the day (the basestock today is much better and more stable and refined). Even so, when used on a short OCI, it is not a biggie. But 20W-50 did not have nearly the same issues because of the viscosity of the low-end basestock (20 weight instead of 10).
I have the feeling that 10W-50 is a synthetic (probably PAO based). The spread stuff does not apply to synthetics so that would be fine. 10W-60 is a factory fill on some high-end cars now.
With regard to the 30 point viscosity spread stuff: what is being talked about has to do with shear down from the heavy Gp VI and VII add packs. What I think you are specifically recalling is dino 10W-40 from back in the day (the basestock today is much better and more stable and refined). Even so, when used on a short OCI, it is not a biggie. But 20W-50 did not have nearly the same issues because of the viscosity of the low-end basestock (20 weight instead of 10).
I have the feeling that 10W-50 is a synthetic (probably PAO based). The spread stuff does not apply to synthetics so that would be fine. 10W-60 is a factory fill on some high-end cars now.
marine_2003
Member
I use the Motorcraft Racing FL-1HP on my mustang. I also use the 20w-50 Valvoline VR-1 Racing Oil. Love it. Runs like a brand new engine every time I change the oil and filter.
mustangjoe87
Member
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