I just changed the oil in my new motor. I had 5-30W for break in. I changed that twice and just put in 10-40W. Idle pressure fully warm is 20-25psi. By 1,500rpm it's on the 70psi relief. I've heard stories of worn front cam bearings, worn cam/cam sensor gears, and stripped/broken pump shafts. I'm getting ready to take this thing on a 300 mile trip and at 2,500rpms, it's going to be at 70psi the whole way. Should I switch back to the thin stuff or does it really matter?
Downside of too much oil pressure?
- Thread starter cool 84
- Start date
I had the same issue cool 84. I had fresh rebuild and oil pressure was 25 at idle and 70 at 1800-2000 rpm's (HOT). My advice is put the weakest bypass spring that came with your oil pump kit. I believe it is orange in color. This should address your concern. Mine is now 60 psi at 1800-2000 rpms HOT. It is 70-72 cold at startup. It will not affect hot idle oil pressure.
As far as high oil pressure affecting cam sensor gears, worn cam bearings and broken oil pump shafts I am not going to debate that it will not happen as it probably does in some cases. However there are precautions you can take to address these issues.
HTH..
Mike Banas
87GN
As far as high oil pressure affecting cam sensor gears, worn cam bearings and broken oil pump shafts I am not going to debate that it will not happen as it probably does in some cases. However there are precautions you can take to address these issues.
HTH..
Mike Banas
87GN
Red Regal T
Senior Member
- Joined
- May 24, 2001
When you first put in new oil, oil pressure is always higher. Once you put a couple hundred miles on it, it will come down. Also, at constant hiway speed, your oil gets very hot and your pressure will be lower. You don't have a problem. 
A couple of points.
First, the higher the pressure, the higher the load on the oil pump drive, and on the front cam bearing. Higher load may not cause an immediate problem, but higher is higher- over time, it has to have an effect. If you rebuild often, probably not an issue at all (By often, I mean like 50,000 miles, instead of 200,000 miles)
Second, higher pressure means higher flow. Most places, not a problem. But unless the engine was built for the higher pressure, you may end up with more oil on the cylinder walls than you need. And more to the valve stems. Not a wear problem, but it may mean more oil that gets by the oil rings, and more deposit in the combustion chamber. Could mean more knock, too.
So, yeah, in general, higher is better. But like most things, there are some trade-offs. The "rule of thumb" that I've heard for the Buick is 10 psi for every 1000 rpm. So, for a 6,000 rpm engine, you would need 60 psi. More than that may not be helpful.
First, the higher the pressure, the higher the load on the oil pump drive, and on the front cam bearing. Higher load may not cause an immediate problem, but higher is higher- over time, it has to have an effect. If you rebuild often, probably not an issue at all (By often, I mean like 50,000 miles, instead of 200,000 miles)
Second, higher pressure means higher flow. Most places, not a problem. But unless the engine was built for the higher pressure, you may end up with more oil on the cylinder walls than you need. And more to the valve stems. Not a wear problem, but it may mean more oil that gets by the oil rings, and more deposit in the combustion chamber. Could mean more knock, too.
So, yeah, in general, higher is better. But like most things, there are some trade-offs. The "rule of thumb" that I've heard for the Buick is 10 psi for every 1000 rpm. So, for a 6,000 rpm engine, you would need 60 psi. More than that may not be helpful.
I don't fully understand the points here, they really don't address yes or no. I have never heard of specifications for "higher" oil pressure asked by a engine builder. Bearing clearances and weight of oil attribute to higher pressure, with a given flow rate of the factory pump, it is obvious that a car with higher pressure, actually has less flow(provided you are at pump capacity(off bypass)), so there is mixed feelings about what is better. We could see more flow/pressure out of the stock type pump with the Duttweiler pump setup because of the more efficient plumbing than the factory filter adaptor/internal pickup setup.
You do not need the high pressures noted in the above posts. I would not stress the timing chain/gears/cam bearings over something you do not need. The STOCK oil pressure on these cars is WAY lower then most think is good, and there is no debate that the factory built the best and most long lasting engines PERIOD.
On a side note. With the bearing clearances in my S2 motor with 20W50 oil, I only saw 65-70 PSI at WOT (7200 RPM's) and I have had no bearing issues to date at these pressures, but I rebuilt sooner than 50k miles. I would have liked more, but what are you going to do when you are looking at the guage 1/2 way down the track. 15psi after the run at idle.
Just stating my experience. Take it or leave it.
Red Regal T
Senior Member
- Joined
- May 24, 2001
I don't know why you guys have such high oil pressure. Either you're using too heavy an oil, or these values are not hot oil values.
I'm using 10-40w oil and a PF52 filter. I have a well used high volume front cover with Kenne-Bell booster plate. I ported the oil holes in the cover and block. Rods and mains are at .0025. Rod side clearance was pretty tight. Turbo is new for what it matters. I'm using the same guage that read 0 at idle on my old motor. The last time I had the car out I purposely drove it hard for a few miles and 1,500rpm and above was still on the pressure relief. I haven't added the oil cooler yet either.
Is there any reason I shouldn't go back to 5-30 to lower pressure a little? Maybe when I switch to synthetic the pressure will drop a little. This is a little annoying because I let the car warm up for 15 minutes in the morning until pressure drops off of 70psi before I drive it.
Is there any reason I shouldn't go back to 5-30 to lower pressure a little? Maybe when I switch to synthetic the pressure will drop a little. This is a little annoying because I let the car warm up for 15 minutes in the morning until pressure drops off of 70psi before I drive it.
i would always be worried about my oil pressure.. everyone not used to buicks would be like 'holy **** thats too low!!'
with my electric autometer gauge.. cold start... the gauge would shoot straight up or a little past straight up.. so 50-55psi... hot idle would always be a hair below the 1st tick.. which is 12.5psi.. kinda scary.. but i guess normal
with my electric autometer gauge.. cold start... the gauge would shoot straight up or a little past straight up.. so 50-55psi... hot idle would always be a hair below the 1st tick.. which is 12.5psi.. kinda scary.. but i guess normal
Red Regal T
Senior Member
- Joined
- May 24, 2001
I'd say, sure, go back to a lighter weight and see what happens. It will have to read lower with lighter weight.
Red Regal T
Senior Member
- Joined
- May 24, 2001
Originally posted by TType84
i would always be worried about my oil pressure.. everyone not used to buicks would be like 'holy **** thats too low!!'
with my electric autometer gauge.. cold start... the gauge would shoot straight up or a little past straight up.. so 50-55psi... hot idle would always be a hair below the 1st tick.. which is 12.5psi.. kinda scary.. but i guess normal
I don't trust electric oilpressure gauges. jmo
Lee Thompson
New Member
- Joined
- May 24, 2001
Cool 84
A high volume front cover and a booster plate is a little too much.
I would remove the booster plate. If the gear cover has the passage opened up you will need another stock gear cover. From what I hear syn. oil will be thinner when cold and thicker when hot than petroleum based oil.
A high volume front cover and a booster plate is a little too much.
I would remove the booster plate. If the gear cover has the passage opened up you will need another stock gear cover. From what I hear syn. oil will be thinner when cold and thicker when hot than petroleum based oil.
Re: Cool 84
Thanks Lee. I might remove the plate. I'll probably wait until summer and see how much the pressure falls off. I installed the plate on my last motor to bring idle pressure from 0psi to 5psi lol. I guess it's too much with a properly built motor.
Thanks Lee. I might remove the plate. I'll probably wait until summer and see how much the pressure falls off. I installed the plate on my last motor to bring idle pressure from 0psi to 5psi lol. I guess it's too much with a properly built motor.
The 10 PSI/ 1K RPM, as far as I can tell was started by Grumpy, or Smokey.
I find it hard to believe that an oil pump can cause the cam to flex enough to eat out the front bearing. If it was due to side loading issues then the rear bearing (or #2) would also be eaten out.
I've run the tall cover a couple of times, and haven't seen any real benefit in a street motor.
If all one is using is the stock windage tray, then oil control is only going to be marginal at best. A well designed scarper, or true windage tray would be good answers to keeping the oil where it should be.
But, my Gn doesn't run 9s.......
Russ Merritt
New Member
- Joined
- Aug 11, 2002
I myself wonder why anyone uses oil thicker than 5/30............
Unless the engine is on it's last leg, 5/30 is more than enough. With a HV pump and booster plate, you shouldn't use anything thicker.
Unless the engine is on it's last leg, 5/30 is more than enough. With a HV pump and booster plate, you shouldn't use anything thicker.
I have a ATR high volume pump and use 20w-50 race oil and get close to or over 100 psi when I first start it up.At idle it is about 40 psi at full temp.After it warms up I get close to 60-70 psi under normal driving but under boost it back around 100 psi and I have drove this all the way to michigan with no problems and raced all nite and then drove it back home to IL some 300 miles and not once Have I had any problems.I'm sure some will say thats probably to much pressure but Like I've always said to much oil pressure(too a limit) is always better then not enough.Just so you understand I've had the same motor in there for close to 60,000 miles running low 11's all day long with 25psi of boost and even drove it to CO to a race before rebuilding it and had the same oil pressure,So I would think any thing under 100 psi under full boost is going to work.Just my .2 cents.
And If you really want to know I think there is probably just as many pros and cons to having too much as there is too little.You just have to make your mind up to as what you are ok with.
And If you really want to know I think there is probably just as many pros and cons to having too much as there is too little.You just have to make your mind up to as what you are ok with.
Yes, you don't understand. An engine builder can build a "loose" engine, which takes lots of flow, or a "tight" engine, which limits flow. Oil pumps come in high volume and not-so-high, with springs to set the bypass pressure. Depending on the engine builders preferences, you can have high pressure or not, and high flow, or not. If you run high pressure on a "loose" engine, then you will get a lot of oil flow, maybe more than needed, and you can overload the oil rings.
Last time I looked, the oil pump was driven off the front of the cam on Buick V6 engines. The load from driving the pump makes the drive gears push apart, putting a side load on the front cam bearing. In addition, the higher load on the cam means higher loading on the timing chain, which also loads the front bearing.
The 10 psi/thousand rpm is related to the pressure needed to force oil into the crank, while centrifugal force is trying to push it out. Engines with larger diameter crank bearings need more- but not it the Buick engine is "larger" or not. The "Power Source" recommends 80 psi for a racing engine- sounds high to me, for a street engine.