Oil pressure low.. Danger?

[AlcHEmiE]

My oil pressure gauge is reading kinda low. When i first start the car in Park it reads about 35-40. But once i put it in drive it just gets progressivley lower untill it hits about 10.. Is this a faulty sensor prehaps? I dont notice and decrease in performance, and the engine still runs smooth.. Should i worry about this?

 

[limomanb]

10 seems a little low. Mine goes to about 20 when warm idling and up to about 60 or so when cruising. Check the Oil Sending Unit for leaks...underside of the engine near the firewall, drivers side.

 

[redc4corvette]

HA HA THAT IS NOT GOOD IS IT ??
well you should have an lt1 350 engine and I know by the book that with the engine warm at 2,000 rpm's your oil pressure should be 18 psi factory spects.

10 lbs at idle is not uncommon for an lt1 just change the oil when it is due.

 

[AlcHEmiE]

HA HA THAT IS NOT GOOD IS IT ??
well you should have an lt1 350 engine and I know by the book that with the engine warm at 2,000 rpm's your oil pressure should be 18 psi factory spects.

10 lbs at idle is not uncommon for an lt1 just change the oil when it is due.

Actually its a L98.. Is that still normal? I doesnt really worry me because the car runs fine.. But im going to ghange my oil now anyhow.. Whats the procedure to reset the "Change Oil" light on the diag screen? Thanks

 

[plumcrazy]

wow, mine is unusually high then 65-68 cold and 38-45 warmed up and
50-55 while driving. is this normal good fresh oil 10-30 and filter. had it
changed twice with in a thousand miles when we got it to flush it out not
sure how the previous owner took care of it.

 

[vader86]

No, thats not within factory specs, and its not good.

When you crank the car, it should jump to the mid 50's idling, and a hot idle will be in the high 20's-low 30s.

When cruising around, anytime your foot is on the gas it needs to be over 50psi, and at full throttle it really needs to be about 60.

If its not, replace the sending unit first, its stuck onto the back of the intake manifold, and youll have to remove the wiper motor and/or the distributor to get it.

Otherwise, replace the oil pump with a Melling unit.

If its still low, its the bearings and you might want to baby it until you can afford to pull the motor.

 

[vetteboy86]

So how far off does the oil pressue have to be to set off an indicator light?

Craig

 

[Moonunit 451]

I think
vader pretty well nailed it. Rule of thumb is your pressure should be at least 10 lbs over your revs. At 800 R's you need to be at 18, at 1200R's 22, and so on.

 

[AlcHEmiE]

But if i spun a bearing, or was in danger of doing so.. Wouldnt i notice a big power loss?

 

[vader86]

If you spun one, you'd damn well know it. Youll hear the knocking.

The oil pressure has to drop below about 4psi at idle to have the warning light come on, that thing is useless. Your engine could be blown long before it ever turns the warning light on.

 

[AlcHEmiE]

Hmm.. so with 75k on the clock, what do you think, in your best opinion, the chances of it being a bearing and not a $20 sensor/Pump.. Just take a guess. Because if its not a cheap fix, im not in the "financial" position to fix it.. I'll just sell it.

I do hear a ticking from the pass. side.. But it isnt THAT loud.. You have to pop the hood and stand on that side to even notice it

*sry, nothing but problems from day 1... just venting a little*

 

[Moonunit 451]

No way to even guess on this one. Try the preliminaries first, and just hope. The ticking could be a lot of things but nit the bottom end. Prolly the injectos, that would be normal.

 

[Vettefan87]

If you had lower end engine noise you would know it as soon as you turned the key. Your oil isnt a milky color or anything is it?

 

[vader86]

I think its probably your injectors, a spun bearing will usually be loud.

 

[GeorgeT]

Before doing anything, put an accurate mechanical gauge on it and see what the "real" pressure is. You may have a bad sending unit.

 

[AlcHEmiE]

Nope, oil was black when i changed it yesterday

 

[laborisfree]

My 84 with 91k on it starts off at about 68psi then drops to 62 at highway speeds. It drops to 35 or so at idle and runs at right around 200degrees. So from what I am seeing my 84 is in the optimum range. Is that correct?

 

[vetteboy86]

Am I the only one that thinks 18 psi of oil pressure is too low? I guess my car is really ****** because at cold start up it is about 68-70 psi. At cruising speed (55mph) it is 55psi, and at an idle with the oil temp 200 it is about 45. Obviously these numbers change with oil temp, and the amount of miles on the oil. My owners manual says between 35 and 45 psi Depending on engine temp. My next question would be how much does brand and type of oil change these figures?


Craig

 

[vader86]

My 84 with 91k on it starts off at about 68psi then drops to 62 at highway speeds. It drops to 35 or so at idle and runs at right around 200degrees. So from what I am seeing my 84 is in the optimum range. Is that correct?

Youre golden.

 

[vader86]

Am I the only one that thinks 18 psi of oil pressure is too low? I guess my car is really ****** because at cold start up it is about 68-70 psi. At cruising speed (55mph) it is 55psi, and at an idle with the oil temp 200 it is about 45. Obviously these numbers change with oil temp, and the amount of miles on the oil. My owners manual says between 35 and 45 psi Depending on engine temp. My next question would be how much does brand and type of oil change these figures?


Craig

Yes 18 is low. I havent noticed much variation between brand or type, but I have with weight of the oil.

15w50 will have a higher idle pressure than 10w30 or 5w30, but I didnt notice any real difference between the Castrol GTX and the Mobil 1 i run now, back when i switched over.

K&N oil filters gave me a slightly higher pressure over Mobil or Purolator though.