Let's settle this oil pressure debate.....
I aim for 15-20 psi at hot idle with all of my engines, which is really double what you actually need. I haven't had an oil related failure with any of my engines.
More than 20 psi oil pressure at hot idle just robs power and increases the risk of oil aeration with no benefit. Higher oil pressure doesn't correlate to higher flow. The bearing clearance, temperature, pressure from combustion, the oil's viscosity, and the oil's pressure-viscosity coefficient all dictate the flow. Oil pressure is just there to be ready to dump oil into the bearing when the wedge opens up each rotation. It doesn't take much pressure to accomplish this. It needs increase with rpm only because the time to fill the oil wedge gets shorter and shorter with rpm.
Unless we're talking about 1000+ hp engine, set the main and rod bearing clearances at .0020-.0025", put a 30 grade oil in it, and sent it.
More than 20 psi oil pressure at hot idle just robs power and increases the risk of oil aeration with no benefit. Higher oil pressure doesn't correlate to higher flow. The bearing clearance, temperature, pressure from combustion, the oil's viscosity, and the oil's pressure-viscosity coefficient all dictate the flow. Oil pressure is just there to be ready to dump oil into the bearing when the wedge opens up each rotation. It doesn't take much pressure to accomplish this. It needs increase with rpm only because the time to fill the oil wedge gets shorter and shorter with rpm.
Unless we're talking about 1000+ hp engine, set the main and rod bearing clearances at .0020-.0025", put a 30 grade oil in it, and sent it.
Launching!
Joined: Mar 2019
Posts: 267
Likes: 171
I also recommend against diesel oil in gas engines for a few reasons.
1. Wrong type of ZDDP. Diesel oil contains ZDDP bonded with primary alkyl groups which gives the oil more thermal stability and oxidative stability, but is less effective at wear protection. Gas oils contain ZDDP bonded with secondary alkyl groups for greater wear protection.
2. Diesel oils contain much higher amounts of ashless dispersants. This is to combat the heavy soot in dirtier diesel crankcases. It's mostly a waste in gas engines where soot isn't a concern. Acidic growth is the main concern with gas engines which dispersants can't do anything about.
3. Diesel oils tend to contain lower amounts of anti-foaming agents since since diesel engines don't turn high enough rpm to make frothing/foaming a major concern. Gas oils contain higher concentrations to keep down foaming at the higher rpm that gas engines typically see.
The saving grace for diesel oil is the base oils they use tend to have a higher pressure-viscosity coefficient, making them less reliant on the additive package for wear protection. This is why they do hold up well in boosted engines for short change intervals.
Two things here... For a street car, operating oil temperature runs much closer to coolant temperature than ambient temperature. In several cars I've studied across many different climates, I haven't observed more than a 10*F difference in operating oil temperature whether it was 20*F or 100*F ambient with the same oil brand/grade and driving style. A greater than 10*F difference was observed when switching to a higher oil grade. This is logical since higher viscosity oil generates more hydrodynamic friction, and where there's friction, there's heat. I would just run 5w-30 year around.
I also recommend against diesel oil in gas engines for a few reasons.
1. Wrong type of ZDDP. Diesel oil contains ZDDP bonded with primary alkyl groups which gives the oil more thermal stability and oxidative stability, but is less effective at wear protection. Gas oils contain ZDDP bonded with secondary alkyl groups for greater wear protection.
2. Diesel oils contain much higher amounts of ashless dispersants. This is to combat the heavy soot in dirtier diesel crankcases. It's mostly a waste in gas engines where soot isn't a concern. Acidic growth is the main concern with gas engines which dispersants can't do anything about.
3. Diesel oils tend to contain lower amounts of anti-foaming agents since since diesel engines don't turn high enough rpm to make frothing/foaming a major concern. Gas oils contain higher concentrations to keep down foaming at the higher rpm that gas engines typically see.
The saving grace for diesel oil is the base oils they use tend to have a higher pressure-viscosity coefficient, making them less reliant on the additive package for wear protection. This is why they do hold up well in boosted engines for short change intervals.
I also recommend against diesel oil in gas engines for a few reasons.
1. Wrong type of ZDDP. Diesel oil contains ZDDP bonded with primary alkyl groups which gives the oil more thermal stability and oxidative stability, but is less effective at wear protection. Gas oils contain ZDDP bonded with secondary alkyl groups for greater wear protection.
2. Diesel oils contain much higher amounts of ashless dispersants. This is to combat the heavy soot in dirtier diesel crankcases. It's mostly a waste in gas engines where soot isn't a concern. Acidic growth is the main concern with gas engines which dispersants can't do anything about.
3. Diesel oils tend to contain lower amounts of anti-foaming agents since since diesel engines don't turn high enough rpm to make frothing/foaming a major concern. Gas oils contain higher concentrations to keep down foaming at the higher rpm that gas engines typically see.
The saving grace for diesel oil is the base oils they use tend to have a higher pressure-viscosity coefficient, making them less reliant on the additive package for wear protection. This is why they do hold up well in boosted engines for short change intervals.
TECH Apprentice
Joined: Sep 2016
Posts: 347
Likes: 10
Hello All,
Thanks Gameova for making this awesome thread with pictures to back it up.
My Bearings looked even worse than that when I removed the engine for inspection (I kept seeing metal in the oil). I have a thread on this I made some where. Long story short, when I took it to the machine shop, they mentioned: "Why did you even bring this motor in? The wear marks on the bearing are scuffs, this is going to happen - you should have ran this motor harder and broke it in properly, give it some throttle! We are going to re-clearance everything for you, throw it in, and run it hard!"
Before my "engine failure" (that my mind had convinced itself of, as I am extremely paranoid (it sucks, trust me)) - my Hot Idle after a race/pull to 6800rpm was 25 psi, and about 60psi WOT,
Again, my bearings looked even worse than that, and the machine shop mentioned that kind of bearing wear is nothing, and is not by any means indicative of a failure.
Thanks,
Andy
Edit:
I didn't make it clear - the reason I thought my motor was failing at the 9,000mi mark, was because the 25psi hot idle... rather than the 40psi hot idle when the motor was "new" - sometimes, you just gotta learn to truly learn.... can't just read everything to learn.
Oil properties:
5w-30 Edge GTX
Idle @ 800rpm
25 psi hot idle (40 psi when motor was new)
Thanks Gameova for making this awesome thread with pictures to back it up.
My Bearings looked even worse than that when I removed the engine for inspection (I kept seeing metal in the oil). I have a thread on this I made some where. Long story short, when I took it to the machine shop, they mentioned: "Why did you even bring this motor in? The wear marks on the bearing are scuffs, this is going to happen - you should have ran this motor harder and broke it in properly, give it some throttle! We are going to re-clearance everything for you, throw it in, and run it hard!"
Before my "engine failure" (that my mind had convinced itself of, as I am extremely paranoid (it sucks, trust me)) - my Hot Idle after a race/pull to 6800rpm was 25 psi, and about 60psi WOT,
Again, my bearings looked even worse than that, and the machine shop mentioned that kind of bearing wear is nothing, and is not by any means indicative of a failure.
Thanks,
Andy
Edit:
I didn't make it clear - the reason I thought my motor was failing at the 9,000mi mark, was because the 25psi hot idle... rather than the 40psi hot idle when the motor was "new" - sometimes, you just gotta learn to truly learn.... can't just read everything to learn.
Oil properties:
5w-30 Edge GTX
Idle @ 800rpm
25 psi hot idle (40 psi when motor was new)
Last edited by AndyTA; Jul 11, 2019 at 12:15 PM.
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
Oh I know, was just putting pics with my claim. Not you, but some people like to see hardcore evidence, and your post just made me remember that I had some pics in my phone. This thread, with the actual pics of the bearings out of my motor, along with the pics of a mechanical gauge, should put all rumors and flat out bad info to bed.
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
Hello All,
Thanks Gameova for making this awesome thread with pictures to back it up.
My Bearings looked even worse than that when I removed the engine for inspection (I kept seeing metal in the oil). I have a thread on this I made some where. Long story short, when I took it to the machine shop, they mentioned: "Why did you even bring this motor in? The wear marks on the bearing are scuffs, this is going to happen - you should have ran this motor harder and broke it in properly, give it some throttle! We are going to re-clearance everything for you, throw it in, and run it hard!"
Before my "engine failure" (that my mind had convinced itself of, as I am extremely paranoid (it sucks, trust me)) - my Hot Idle after a race/pull to 6800rpm was 25 psi, and about 60psi WOT,
Again, my bearings looked even worse than that, and the machine shop mentioned that kind of bearing wear is nothing, and is not by any means indicative of a failure.
Thanks,
Andy
Edit:
I didn't make it clear - the reason I thought my motor was failing at the 9,000mi mark, was because the 25psi hot idle... rather than the 40psi hot idle when the motor was "new" - sometimes, you just gotta learn to truly learn.... can't just read everything to learn.
Oil properties:
5w-30 Edge GTX
Idle @ 800rpm
25 psi hot idle (40 psi when motor was new)
Thanks Gameova for making this awesome thread with pictures to back it up.
My Bearings looked even worse than that when I removed the engine for inspection (I kept seeing metal in the oil). I have a thread on this I made some where. Long story short, when I took it to the machine shop, they mentioned: "Why did you even bring this motor in? The wear marks on the bearing are scuffs, this is going to happen - you should have ran this motor harder and broke it in properly, give it some throttle! We are going to re-clearance everything for you, throw it in, and run it hard!"
Before my "engine failure" (that my mind had convinced itself of, as I am extremely paranoid (it sucks, trust me)) - my Hot Idle after a race/pull to 6800rpm was 25 psi, and about 60psi WOT,
Again, my bearings looked even worse than that, and the machine shop mentioned that kind of bearing wear is nothing, and is not by any means indicative of a failure.
Thanks,
Andy
Edit:
I didn't make it clear - the reason I thought my motor was failing at the 9,000mi mark, was because the 25psi hot idle... rather than the 40psi hot idle when the motor was "new" - sometimes, you just gotta learn to truly learn.... can't just read everything to learn.
Oil properties:
5w-30 Edge GTX
Idle @ 800rpm
25 psi hot idle (40 psi when motor was new)
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Verdad Gallardo TECH Apprentice
Joined: Sep 2016
Posts: 347
Likes: 10
Ahh yes, glitter oil. One of the reasons I pulled my motor a few years ago, thought it was hurt. Bearings were perfect, to this day, I STILL have glitter oil EVERY oil change, yet...everything is perfectly fine. Cam bearings are mint...lifters are mint, I give up. I just learned to live with it.
On the other hand, this is *exactly* what pisses me off. You can do an internet search for HOURS upon HOURS, read threads upon threads. and every motherf****** will tell you:
(This is on other threads with metal in oil as title/descriptions through out the years from all various car forums around the internet):
"your motor is about to break, I see no metal in my oil, you shouldn't see any"
"If I saw metal like that in my oil, I'd freak"
"Holy s*** stop running it immediately!"
"Glitter in oil is a failing bearing!!"
I've learned over time (and especially recently, and especially after the creation of this thread) how much people just DO NOT KNOW. How much they PRETEND to know.
EVERY oil change of mine for all 9000 of those miles, have had glitter in the oil from the filter, and small metal that would supposedly "make people freak out and get a heart attack on the internet" - yet when I took it to my machine shop, I look stupid because they say "twhy did you even bring this motor in!?" as a joke.
Good riddance.
Can't tell you how much I appreciate this thread.
Sometimes, we forget the simple fact that there is a REASON an oil filter even exists in the first place - because metal is expected, whether it's glitter or a little more.
All in all gauges vary, long as its decent and increases with RPM I don't worry too much about it.
Oh I know, was just putting pics with my claim. Not you, but some people like to see hardcore evidence, and your post just made me remember that I had some pics in my phone. This thread, with the actual pics of the bearings out of my motor, along with the pics of a mechanical gauge, should put all rumors and flat out bad info to bed.
Launching!
Joined: Mar 2019
Posts: 267
Likes: 171
Launching!
Joined: Mar 2019
Posts: 267
Likes: 171
Diesel oil can certainly still get the job done, but it's leaving a narrower margin for error. A drag racing engine that operates at <200*F with only a short burst at WOT probably won't see much negative effects from diesel oil as the run is over before the effects of aeration start to show. Put that same oil in a NASCAR cup engine, where the oil pump inlet temps are 280*F with bearing temperatures >350*F, and it wouldn't last 2 laps around Daytona. The drag racing engine would still benefit from a superior, lower grade oil as the lower friction, lower pressure-viscosity coefficient, and lower oil pressure all translates into quicker ET through free'd up power, everything else equal.
Most cases would be sufficient with a 30 grade. Even boosted applications (up to a point), I wouldn't advice going up to a 40 or 50 grade. I would advise a superior 30 grade. Oils like Driven LS30 5w-30, Red Line HP 5w-30, HPL Bad *** 5w-30, and LAT Racing 5w-30 put Rotella, Delo, and Delvac 15w-40 to shame in terms of oxidative stability, thermal stability, shear stability, aeration inhibition, and friction reduction.
Diesel oil can certainly still get the job done, but it's leaving a narrower margin for error. A drag racing engine that operates at <200*F with only a short burst at WOT probably won't see much negative effects from diesel oil as the run is over before the effects of aeration start to show. Put that same oil in a NASCAR cup engine, where the oil pump inlet temps are 280*F with bearing temperatures >350*F, and it wouldn't last 2 laps around Daytona. The drag racing engine would still benefit from a superior, lower grade oil as the lower friction, lower pressure-viscosity coefficient, and lower oil pressure all translates into quicker ET through free'd up power, everything else equal.
Diesel oil can certainly still get the job done, but it's leaving a narrower margin for error. A drag racing engine that operates at <200*F with only a short burst at WOT probably won't see much negative effects from diesel oil as the run is over before the effects of aeration start to show. Put that same oil in a NASCAR cup engine, where the oil pump inlet temps are 280*F with bearing temperatures >350*F, and it wouldn't last 2 laps around Daytona. The drag racing engine would still benefit from a superior, lower grade oil as the lower friction, lower pressure-viscosity coefficient, and lower oil pressure all translates into quicker ET through free'd up power, everything else equal.
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
Why couldn't you make this thread 3 months ago before I pulled my motor out of internet paranoia!?!?
On the other hand, this is *exactly* what pisses me off. You can do an internet search for HOURS upon HOURS, read threads upon threads. and every motherf****** will tell you:
(This is on other threads with metal in oil as title/descriptions through out the years from all various car forums around the internet):
"your motor is about to break, I see no metal in my oil, you shouldn't see any"
"If I saw metal like that in my oil, I'd freak"
"Holy s*** stop running it immediately!"
"Glitter in oil is a failing bearing!!"
I've learned over time (and especially recently, and especially after the creation of this thread) how much people just DO NOT KNOW. How much they PRETEND to know.
EVERY oil change of mine for all 9000 of those miles, have had glitter in the oil from the filter, and small metal that would supposedly "make people freak out and get a heart attack on the internet" - yet when I took it to my machine shop, I look stupid because they say "twhy did you even bring this motor in!?" as a joke.
Good riddance.
Can't tell you how much I appreciate this thread.
Sometimes, we forget the simple fact that there is a REASON an oil filter even exists in the first place - because metal is expected, whether it's glitter or a little more.
On the other hand, this is *exactly* what pisses me off. You can do an internet search for HOURS upon HOURS, read threads upon threads. and every motherf****** will tell you:
(This is on other threads with metal in oil as title/descriptions through out the years from all various car forums around the internet):
"your motor is about to break, I see no metal in my oil, you shouldn't see any"
"If I saw metal like that in my oil, I'd freak"
"Holy s*** stop running it immediately!"
"Glitter in oil is a failing bearing!!"
I've learned over time (and especially recently, and especially after the creation of this thread) how much people just DO NOT KNOW. How much they PRETEND to know.
EVERY oil change of mine for all 9000 of those miles, have had glitter in the oil from the filter, and small metal that would supposedly "make people freak out and get a heart attack on the internet" - yet when I took it to my machine shop, I look stupid because they say "twhy did you even bring this motor in!?" as a joke.
Good riddance.
Can't tell you how much I appreciate this thread.
Sometimes, we forget the simple fact that there is a REASON an oil filter even exists in the first place - because metal is expected, whether it's glitter or a little more.
Thread Starter
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
. You get that thing to the track yet?? If not, do I need to fly down there and run it??!!
Originally Posted by Game ova
Lol, yea....gotta break that roller cam in . You get that thing to the track yet?? If not, do I need to fly down there and run it??!!
. You get that thing to the track yet?? If not, do I need to fly down there and run it??!!