Oil pressure and oil weight
Thread Starter
Registered User
Joined: Jan 2015
Posts: 26
From: Tx
Oil pressure and oil weight
Im a newbie to the forum and glad to be posting. I used a lot of the advice i found here before i bought my car, so thanks.
I have a 72 cutlass S with a 350 rocket bored 60 over. The seller told me to run 20w50 since the car was built for racing. Question 1 is, does this weight work for driving in town in 60-80 temp? (Bought the car in Michigan) Question 2 is what should my oil pressure be? Im seeing 80 while driving and not sure if thats good or bad. Appreciate the feedback.
- Bluedane
(Admin, I re-posted in newbie forum...could not find a delete function for the other post in General)
I have a 72 cutlass S with a 350 rocket bored 60 over. The seller told me to run 20w50 since the car was built for racing. Question 1 is, does this weight work for driving in town in 60-80 temp? (Bought the car in Michigan) Question 2 is what should my oil pressure be? Im seeing 80 while driving and not sure if thats good or bad. Appreciate the feedback.
- Bluedane
(Admin, I re-posted in newbie forum...could not find a delete function for the other post in General)
Lansing built
Joined: Nov 2011
Posts: 3,332
From: Grand Ledge, MI
Welcome to C.O. I thought I recognized that car. It was on craigslist for a little while (don't recall what city) price was decent also.
I would assume that you have a high volume pump, some of the racers will have to chime on the PSI seems high but pump and oil weight thats plenty of pressure.
Pat
I would assume that you have a high volume pump, some of the racers will have to chime on the PSI seems high but pump and oil weight thats plenty of pressure.
Pat
CH3NO2 LEARN IT BURN IT
Joined: Jul 2010
Posts: 5,649
From: Land of Taxes
If that's what the PO told you to run I would stick close to that weight. Dont put 10W30 in it. You could go to Shell, Rotella T 15W40. I have been using it for years. Ive also had great luck with Schaeffer oil products, 15W40 as well. Read up on Schaeffers products. 80 psi is that at idle or at speed? I will assume at speed, 80 is ok as it sounds like the engine was built to handle that. Whats the psi read with hot oil at idle?
Last edited by droldsmorland; Jan 27, 2015 at 05:45 AM.
Connoisseur d'Junque
Joined: Sep 2010
Posts: 21,183
From: The Hudson Valley
80 psi is high. Not dangerous, just a lot higher than normal.
A normal oil pressure would be 40psi driving, down to about 10-20 at idle, hot.
There is nothing wrong with running 20w50 if you want or need to (though, since it is slower to infiltrate small spaces when cold, some say it provides poorer startup lubrication), but if you've got an entirely unnecessary 80psi, I'd say there's nothing wrong with dropping down to 10w40, or even 10w30, if you still have good pressure with those.
As far as racing: I would question that. Racing is all about getting the most power out of your engine.
If you are running at 80psi, your oil pump is robbing several horsepower to achieve that, and that doesn't sound very racy to me.
If it were me, I'd probably try a thinner grade and see how it behaves.
- Eric
A normal oil pressure would be 40psi driving, down to about 10-20 at idle, hot.
There is nothing wrong with running 20w50 if you want or need to (though, since it is slower to infiltrate small spaces when cold, some say it provides poorer startup lubrication), but if you've got an entirely unnecessary 80psi, I'd say there's nothing wrong with dropping down to 10w40, or even 10w30, if you still have good pressure with those.
As far as racing: I would question that. Racing is all about getting the most power out of your engine.
If you are running at 80psi, your oil pump is robbing several horsepower to achieve that, and that doesn't sound very racy to me.
If it were me, I'd probably try a thinner grade and see how it behaves.
- Eric
'87 Delta 88 Royale
Joined: Dec 2010
Posts: 2,514
From: Margate, England
You say the seller recommends 20w50, what did the engine builder recommend?.
Oil plays a very important part in cooling the engine, it has to remove heat from the bearing surfaces. All else being equal, the thinnest oil that will provide adequate lubrication is the ideal for a race engine.
As Eric said, more oil pressure than you need is wasted power. Modern close tolerance engines use thinner oils than the big lazy units of yesteryear.
Roger.
Oil plays a very important part in cooling the engine, it has to remove heat from the bearing surfaces. All else being equal, the thinnest oil that will provide adequate lubrication is the ideal for a race engine.
As Eric said, more oil pressure than you need is wasted power. Modern close tolerance engines use thinner oils than the big lazy units of yesteryear.
Roger.
Administrator
Joined: Oct 2009
Posts: 42,524
From: Poteau, Ok
Welcome to the site from another Texan. High oil pressure can be a result of reduced oil flow due to viscosity. Summer driving in our higher temps can benefit from the 20/50, however winter driving with the lack of flow may harm your engine. You have to find a happy medium between the two.
Thread Starter
Registered User
Joined: Jan 2015
Posts: 26
From: Tx
If that's what the PO told you to run I would stick close to that weight. Dont put 10W30 in it. You could go to Shell, Rotella T 15W40. I have been using it for years. Ive also had great luck with Schaeffer oil products, 15W40 as well. Read up on Schaeffers products. 80 psi is that at idle or at speed? I will assume at speed, 80 is ok as it sounds like the engine was built to handle that. Whats the psi read with hot oil at idle?
- Bluedane
Thread Starter
Registered User
Joined: Jan 2015
Posts: 26
From: Tx
80 psi is high. Not dangerous, just a lot higher than normal.
A normal oil pressure would be 40psi driving, down to about 10-20 at idle, hot.
There is nothing wrong with running 20w50 if you want or need to (though, since it is slower to infiltrate small spaces when cold, some say it provides poorer startup lubrication), but if you've got an entirely unnecessary 80psi, I'd say there's nothing wrong with dropping down to 10w40, or even 10w30, if you still have good pressure with those.
As far as racing: I would question that. Racing is all about getting the most power out of your engine.
If you are running at 80psi, your oil pump is robbing several horsepower to achieve that, and that doesn't sound very racy to me.
If it were me, I'd probably try a thinner grade and see how it behaves.
- Eric
A normal oil pressure would be 40psi driving, down to about 10-20 at idle, hot.
There is nothing wrong with running 20w50 if you want or need to (though, since it is slower to infiltrate small spaces when cold, some say it provides poorer startup lubrication), but if you've got an entirely unnecessary 80psi, I'd say there's nothing wrong with dropping down to 10w40, or even 10w30, if you still have good pressure with those.
As far as racing: I would question that. Racing is all about getting the most power out of your engine.
If you are running at 80psi, your oil pump is robbing several horsepower to achieve that, and that doesn't sound very racy to me.
If it were me, I'd probably try a thinner grade and see how it behaves.
- Eric
- Bluedane
Thread Starter
Registered User
Joined: Jan 2015
Posts: 26
From: Tx
Welcome to the site from another Texan. High oil pressure can be a result of reduced oil flow due to viscosity. Summer driving in our higher temps can benefit from the 20/50, however winter driving with the lack of flow may harm your engine. You have to find a happy medium between the two.
-Bluedane
Registered User
Joined: Dec 2013
Posts: 180
Your figures sound OK, but I would check those figures with a known good mechanical gauge, and not depend on the electric; it is easy enough to do, and a test gauge can be purchased readily from any local hydraulic supply vendor that services farm/construction equipment. If you are running a flat tappet/hydraulic cam, I would be more concerned about the ZDDP content of the oil, as today's oil has all but eliminated it, with the trend to roller lifters and catalytic converters, O2 sensors, etc!
Connoisseur d'Junque
Joined: Sep 2010
Posts: 21,183
From: The Hudson Valley
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