More Oil Pressure Question
Thread Starter
4th Gear
Joined: Oct 2007
Posts: 4
Likes: 0
From: Hudson FL
More Oil Pressure Question
Hi all.....
I know this topic has been tossed around and around a bunch of times, but I just bought my 3rd vette in 30 years and am seeking opinions;
I just got this 96 C4 LT1 with 135K on it that has been well maintained.
Oil pressure was great when I got it from auction - although very filthy. (45 at 1300 rpm hot)
I changed the oil last week to 5W30 Mobil-1 and now seeing 55 psi at cold startup which generally drops off to 20 psi at hot idle, and 38/39 at cruising 1300 to 1400 rpm.
Cruise speeds of 2000 rpm is slightly over 40. 750 rpm idle still maintains 20 psi.
I was considering a heavier oil, something other than 10w30 Synth but curious how heavy a grade to go.
I just replaced the sender, too - no changes noted.
Any opinions are appreciated.
I know this topic has been tossed around and around a bunch of times, but I just bought my 3rd vette in 30 years and am seeking opinions;
I just got this 96 C4 LT1 with 135K on it that has been well maintained.
Oil pressure was great when I got it from auction - although very filthy. (45 at 1300 rpm hot)
I changed the oil last week to 5W30 Mobil-1 and now seeing 55 psi at cold startup which generally drops off to 20 psi at hot idle, and 38/39 at cruising 1300 to 1400 rpm.
Cruise speeds of 2000 rpm is slightly over 40. 750 rpm idle still maintains 20 psi.
I was considering a heavier oil, something other than 10w30 Synth but curious how heavy a grade to go.
I just replaced the sender, too - no changes noted.
Any opinions are appreciated.
Last edited by SamD; Nov 11, 2007 at 09:12 PM.
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
How do know that it was well maintained if you bought it at auction?
That aside, why are you concerned? The readings are not so low. However, I would go to 20 or up oil unless you live with very cold winters.
5w oil is all about miles per gallon. The car can achieve a higher efficiency rating with thinner oil and the company has determined that the car will make it through the warantee period with the thinner oil. They must therefore recommend the thin oil used to set the MPG for the car and company. That is not the same as saying it is best for the car.
That aside, why are you concerned? The readings are not so low. However, I would go to 20 or up oil unless you live with very cold winters.
5w oil is all about miles per gallon. The car can achieve a higher efficiency rating with thinner oil and the company has determined that the car will make it through the warantee period with the thinner oil. They must therefore recommend the thin oil used to set the MPG for the car and company. That is not the same as saying it is best for the car.
Thread Starter
4th Gear
Joined: Oct 2007
Posts: 4
Likes: 0
From: Hudson FL
Thanks for the reply Chatman -
"Well maintained" is speculative only by appearances and lack of worn out tires, belts, interior, body, headliner, electronics, tight steering, brakes, transmission, etc..etc....
The previous owner may not have changed the oil i the last 120K miles, but from all other aspects of this vehicle, I would have to state my opinion.
Now - you say I would go to 20 or up oil are you referring to a 20w50? or ????? Im confused.
Florida doesnt see much in the way of 30 degree days here.
Your input is appreciated.
"Well maintained" is speculative only by appearances and lack of worn out tires, belts, interior, body, headliner, electronics, tight steering, brakes, transmission, etc..etc....
The previous owner may not have changed the oil i the last 120K miles, but from all other aspects of this vehicle, I would have to state my opinion.
Now - you say I would go to 20 or up oil are you referring to a 20w50? or ????? Im confused.
Florida doesnt see much in the way of 30 degree days here.
Your input is appreciated.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
oh, dear... no. Do NOT use 20-50 in a modern engine. It's a sure fire way to dry it out.
Modern engines have much tighter tolerances and don't need to heavy oils to fill in those gaps. There is a slim chance that the bearings would not see enough flow to be properly protected.
And no, bearings don't wear... they sure has hell better not wear, as they are hydro-static - the crank floats in oil. not much, yes, but it does float.
The pressure numbers you are noting are perfectly ok. the rule of thumb is 10 PSI per 1000 RPM. Those numbers are excellent. Oh, and don't believe the GM gauge as gospel... they are noted for some, er, errors... yes, errors.
Modern engines have much tighter tolerances and don't need to heavy oils to fill in those gaps. There is a slim chance that the bearings would not see enough flow to be properly protected.
And no, bearings don't wear... they sure has hell better not wear, as they are hydro-static - the crank floats in oil. not much, yes, but it does float.
The pressure numbers you are noting are perfectly ok. the rule of thumb is 10 PSI per 1000 RPM. Those numbers are excellent. Oh, and don't believe the GM gauge as gospel... they are noted for some, er, errors... yes, errors.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
I'm not so sure about all that Bogus
I've been running Castrol GTX 20-50 in all my vehicles for almost 30 years.....racing and cruising.
Sure, I've to rebuild motors....but mainly ones that I had recently purchased and in most of those cases I bought the car knowing that the car was on it's last leg and Cheap in price.
Non of the motors I've owned since nearly new or rebuilt myself have ever had any problems......My Troopers (3 of them) all went over 120K miles each and were still running strong when I traded them. Thinking back, I can calculate over a million miles on cars of mine with GTX 20-50
You'll not pry my Castrol GTX 20-50 from my fingers anytime soon.
I've been running Castrol GTX 20-50 in all my vehicles for almost 30 years.....racing and cruising.
Sure, I've to rebuild motors....but mainly ones that I had recently purchased and in most of those cases I bought the car knowing that the car was on it's last leg and Cheap in price.
Non of the motors I've owned since nearly new or rebuilt myself have ever had any problems......My Troopers (3 of them) all went over 120K miles each and were still running strong when I traded them. Thinking back, I can calculate over a million miles on cars of mine with GTX 20-50
You'll not pry my Castrol GTX 20-50 from my fingers anytime soon.
