Oil Pressure- How Much Do You Need And Why 

So I built a 340 in 2000 was going to do the high volume pump thing till my dad advised me being a mechanic in the 50 60 and 70s not to. His take was make sure your clearances are right and cam bearings where good am I would have any trouble with a stock oil pump. 20 years later the engine is still running 45 psi hot idle. Been into 6500rpm many times and still going. Old guys rock. Lol

I love the fact we are getting lessons on better gas mileage whilst a tunnel rammed big block resides in back ground! 😉🤩🖕

Smokey Yunick was a fiend for reducing any unneeded oil pressure to free up horsepower, I've read he often began with the cheapest parts house oil pumps, modified them, and then used them in 100,000 dollar engines. Even Ralph Earnhardt used hardware store screwdrivers for axle keys that wouldn't break.

Facts. I remember back in the day the first engine I rebuilt, I was priming the oiling system prior to starting the engine using a drill and when it started building oil pressure the drill about twisted my adolescent arms into a pretzel because it takes A LOT of power to turn the oil pump and make oil pressure.

I owned an MGB once upon a time that had approximately 40 psi at cold idle. When i revved the engine the oil pressure dropped. after a short warmup the pressure at idle barely registered and disappeared entirely when revved. a complete teardown revealed nothing obvious. i was examining the oil pump when i dropped it on tbe floor and got a bit of unseen dirt in it. i stuck the driven rotor back in and absentmindedly twisted the shaft. the rotor didn't turn, the shaft did. turned out that the pin securing the driven shaft had sheared . when cold there was enough friction on the shaft from the sheared pin to generate some pressure but revving would make everything slip.

I thought the rule of thumb was 10psi/1000rpm, but not a huge difference. BTW, the tangs on the bearing shells are not there to resist rotation of the shells in the rod/cap/main bore. They are there simply to align things during assembly. Some newer engines don't even have the tanks. Bearing crush is what keeps the bearing from spinning in the bearing bore. I've seen several BMW S62 rod bearings that went metal to metal. What happened was that the tangs ripped off the shell and the bearing rotated a bit. Those pieces of tang then gouged the bearing and rod journal (since the backing is steel). It would have been better to not have the tangs there. I replaced the bearings with King bearings, which have more crush and more eccentricity, along with ARP 2000 rod bolts to stave of spinning the bearings.

I've been hearing the 7psi per 1,000 RPM rule of thumb forever but no one could explain what the forces were that determined that. The centrifugal forces explanation seems obvious now that you explain it. Thanks Tony. I just learned something valuable

This is awesome Tony, oil pressure and it's relationship to cooling the rod bearings is one of the most overlooked items that racers and race engine builders miss.Pressure is just the resistance to flow, increased clearances reduce pressure, but that's only part of the story, what a lot of builders don't quite get. I've found you can have great oil pressure and still burn up rod bearings, been there and done that. What I needed was increased oil volume flowing over the journals, to keep the bearing shells cool. Fail keeping them cool, and the plating on the bearings blisters, separates from the steel bearing substrate, like chrome plating bubbling up on an old bumper. The infamous 'glitter in the oil'. Once that happens, it's game over, the bearings need to be replaced pronto, otherwise the plating sluffs off, down to the steel core, and micro-welding takes place, bearing spins, crying and long faces, and a long tow home..

Great info as always. A quick note for my modern engine guys: Remember that these new generation engines are engineered differently designed with different expectations of idle PSI. Hydraulic tensioners do not like 7PSI, and any flavor of Hydraulic Valve timing (Found in basically every new-age engine) is designed around the engine producing closer for 30-40psi. TL;DR, Don't expect your 2020 Focus to like 7PSI idle oil pressure.

Perfect example of why I watch every single UTG video. Yes I've bought merch. Thank you for sharing Tony.

Amazing presentation once again. Uncle Tony speaks off the top of his head, with the detail and sequence of a thoroughly organized engineering editorial. Must be all that writing experience! Thanks UT!

I was just talking about this with a mechanic! He said the same thing! Great video!

Been watching for years and THIS is probably the best info you've put out!! Thank you!!

Probably one of your better informational videos. I was wondering about my low oil pressure during idle. Thanks.

Tony's explanations are excellent!!! Especially when addressing things like this... Just the knowledge, of the effects of proper bearing clearance and the direct corellation of oil pressure and the condition of the bearings is good to know!!!

Uncle Tony you are the best! At age 67 I finally understand the highs and lows of engine oil pressure. Thanks

The rest of the video is pretty informative I just got to make one adjustment. note the tangs of a bearing are not to hold it from spinning the tangs are only a reference point to locate the bearing.. what holds the bearing in place is the "crush" how much the Rod Cap and the connecting rod crush the bearing in. the friction on back of the shells is what keeps the bearing from spinning. I'm not trying to take anything away from you Tony🤗 I just wanted to relate that to other people. 🤗 I think you did that to see if we're paying attention 👍🤗

Thanks for breaking it down. I knew higher oil pressure cost horsepower, but I didn’t know the bottom line for running low oil pressure safely. Great job explaining 👍

I'm so glad we have tony he has helped me tremendously it's so hard to find good no bullshit information I bought a high volume for my 408 I put in my pickup because everyone tells you to but what your saying makes complete sense I'll use thinner oil to compensate for now lol

most people don't know this, glad you did this video!

Finally someone has covered this subject while challenging the myths. I've been wondering about what is right and why for many years :)

Thank you for backing up what I have been saying for years. Also, getting the oil to flow through the motor is cool. Ask anyone who has built a Cleveland.

I DID get something out of this,Uncle Tony!I always thought you needed high oil pressure.This falls under the category of "less is more". This is good to know!

Good of you to bring to light this oil pressure issue. This is something I also learned many moons ago, how parasitic losses both absorb power otherwise available for performance and decrease fuel mileage in the same manner. This type of thing was a big part of what went into my customers engines. The OEMs have only begun to take the parasitic oil pumping losses to the next level as of late. Several manufacturers before, and now Chevy's C8 Corvette have ECM modulated oil pressure, the bypass used to reduce oil pressure to the much lower level required at a lightly loaded cruise condition, and then ramp it up under high load conditions. And some say hot rodding doesn't contribute to improving production cars - I say bullshit.

I never knew this Uncle Tony. I always thought high volume oil pump would be best but, you just educated me on this. You also educated me that sometimes more is not better. It pays to get other opinions and sometimes just listen and not have blinders on. Thank you Uncle Tony. I really appreciate your experience and the time you put into your videos!!! 👍👍

Good vid UT.. you pretty much hit everything spot on. I absolutely love the basics being explained. Your waaayyy better then I am at explaining why. I just tell people to do it or not to.. thanks for the upload! (5 psi per 1k + about 10 at idle is all you need if you are running 100% stock internals meaning no mods at all) if it's modded.. take the 7.. oil weight is a huge thing.. it would be cool to see your opinion on higher pump, lower weight.. vs higher weight less pressure. There's a serious science to this. And you can explain it better then anybody. Thanks again UT

Thanks for explaining this. Haven't been able to find anything explaining pressure and where it should be. I appreciate your knowledge and videos. Keep it up.

Excellent video! Thank you. That helps explain why my big block with a melling high volume pump with a hemi pickup gets so hot!

This may be the first video I ever share. And, subtly probably one of your most important yet Tony! Great! Stuff!

Tony: Thanks for the insight into oil pressure and it's causes. Any information about oil pumps, especially SBC oil pumps, is greatly appreciated as well. The reason for this is that I can't find a great deal of information about oil pumps with the cause and effect situations in my studies. Again, you help is well taken seriously.

So glad you are covering this!

Love your old school knowledge! Keep it up! You have leaps and bounds more knowledge than most of these builders on YT!

Thanks Tony, your advice is once again, spot on. Running a budget ring gapped turbo 360 and 351w. Both with stock oil pumps, both work really well. Windage trays in both sumps.

It's hard to find someone like you, to talk to, about this exact subject! Thanks for all the info!!!

One of the top misunderstood engine rebuild topics! I think I read about this in a Hotrod magazine once back in the 80's. Glad you addressed it here again.

I'm so happy he got it right concerning oil pressure. So many places wrongly advise high oil pressure is a goal. Not just cars but many heavy duty truck engines also run with low oil pressure from the factory. My International 392 cu in engine has been running less than 10 psi at idle for more than 40 years and I don't baby that work truck.

I hate when I ask someone why they do something and all they can say is "well it's just what you do" or "this is just how I've always done it and it works fine". I'm not a hot rodder or even really a "tuner" (I just found this channel because I got an 88 Jeep YJ with an Edelbrock carb - first time dealing with a carburetor and was looking for videos about getting it set right) but still found this video hugely enlightening...the bit about how roller bearings will skid on oil reminded me of another video I had watched about how bowling lanes are pretty finely tuned by how much and what kind of oil is put on them and led to an "ohhhh so THAT'S how those things work" moment. I would LOVE to see more videos on topics like this that really dig into exactly WHY certain values are what they are...why do we run thermostats of a certain value? Why do we set spark timing where we do? What changes when we modify these values?

Again, You are bang on Tony. I grew up with the old - and I mean "old" school mechanics who had dirt floors in there shops and nicotine and oil / varsol permanently stained fingers. But man O man, did they know how to make mechanical things work and work better than stock in a lot of cases. I wish I could have absorbed more of their wisdom and knowledge but I retained as much as I could, and that knowledge has given me a great base to be able to work on or "hot rod" the modern engines as well. Love your channel and you knowledge man 👍 I would happily push a broom around your shop and even clean the toilets just to be able to be around you when you're thinking out loud. PS; I'm 60 years old, so it ain't no spring chicken doin the talk'n here.

We learned that lesson back in the early eights. Playing with circle track cars, one year we say we were not going to have time to finish a new car and a new engine. A friend racing ARCA recommended a builder to us and we had a engine built. On delivery the parts list shown a stock mopar oil pump. When questioned his response was try it you will like it. He then ask about any problems in the past with engines. The only thing we ever had was a couple bearing failures. At that point he responded that we must have been running a high-volume oil pump and yes, we had been. He then informed us all were doing was overheating the oil and pumping it all to the top of the engine at which point the oil pump sucked air and the pressure drops to oh shit levels.

Thank you so much, I could never find any help with oil pressure in my LS2 so this is just what I needed

Always great info! I've messed with oil pressures and oil viscosity for years and ruined a motor or 2 by bad thinking. Best advice is to stay as close to stock as possible if using stock specs on rotating assembly. On an old engine with low oil pressure a high volume oil pump may buy you a few more years. I used 50 w in an old engine thinking it would provide more cushion on my rods and ended up starving front 2 rods! So oil viscosity and not knowing what your doing can have dire consequences

So glad you brought up the loose builds and more flow = more heat leaves the journal and less resistance to flow takes a load off the system.. The primary purposes for lubrication is lubrication and includes cooling. I love the oil wedge comments and how the oil enters the journal- it's why the oil holes in the shafts within the journals are located where they are. To maintain the oil wedge, where it feeds into the journal plays into the place where the journal is put under load- the compression stroke and is to cushion the journal as it loads. I hear other rebuild guys talking about journal radius and side clearances. This does play into how well the oil will flow through the bearing- too much clearance will result in an oil pressure drop in the system and the oil viscosity previously run with a different clearance won't provide a familiar result. When refitting old Dodge crank journals with fresh shells, what advice can you offer for appropriate clearance? Not just what the plastigage says, but side clearance. What kind of journal side radius should I check for on a rejuvenated shaft journal and should I be chamfering the shells? I realize that loose is good, but to much of a good thing can be bad, too. Thx in advance.

There are two factors used for calculating horsepower requirements for pumps, flow and pressure . reduce either one and there is a reduction in required HP. Great video Tony.

My old 55 Studebaker 259 idles at 10 psi hot , I did a lot of clearance work to the oil pump and bearings too . Always thought that was low , but it is the way the engineers designed it . Thank you Tony , another Tony from Hemet , CA.

I had a good 1970 360 F.E. with 20 p.s.i. and wanted to bump it up. I added a full qt. of Lucas oil stabilizer and got 80 p. s.i. WAY too much! Drained it and put a Pint of Lucas in and got 40 p.s.i. @5000 rpm. It was much happier and so was I!

Solid advice as usual UT 💪🏻 Such a common mistake here in Australia on the old Holden V8 engines. People will put a high volume pump on a very mild engine and just end up filling the rockers full of oil and not allowing enough time for it to drain back. Appropriate mods / oiling system work it can be done, but so many combos its not even applicable. Worst one I saw was sustained high-ish rpm (drag race) with a high vol pump which starved the bottom end and spun a bearing or two.

Thank you for crediting Bill Jenkins and especially (my hero!) Smokey Yunick. Over the years Yunick in his HP series books and contributions to Circle Track Racing magazine has enlightened many on the basic principles and physics of engines and related ancillary systems resolving the many unfounded 'myths' that have been around much too long. Keep in mind he 'schooled' the GM engineers more than once proving what actually happens inside motors vs the misconceptions they held for decades. Don't forget the number of times he outsmarted the NASCAR tech inspectors, some of which is legend. He did the same moving to Indy then later to Trans Am. A genius, always looking for answers that most never considered.

UT, what makes you great , among other things is youre true passion !!! KUDOS to you man ..

Good info for durability. External oil cooler helps in certain applications. VW bug were air cooled and oil cooled as were Buells. Early engines had no pump, just splash but they had solid lifters, low RPM. Oil pressure on old engines was low like 4 psi at idle, again low compressio, low RPM, solid lifters.

Luv the wisdom. Its like gettin ya papers, i used to know what it did ,but now i know why it does it.

Thanks for the education. I learn something new every time I come to your page.

Thanks Tony for the teaching you share

Great video finally some true facts. Also I wish somebody would do a video of oil pressure vs oil volume, completely different things.

Thank you for this. So interesting. This has put my mind at rest regarding my Healey 3000 oil pressure when engine is hot.

Love it learned in the late 70s about facing round track love the real old school info

Tony, Tim Arnott here, GREAT vid!!...and you are correct sir!!...my Pontiac has the RAIV Pump/pickup, usually described as high vol/pres.......it makes about 585 hp......i use a 10-40 wt cuz 20-50 wud create to much pres.....warm, at idle, i got 25psi........as soon as i get to 2500 rpm, i got 75 psi, all the way up to 6200 rpm......thats plenty......my brother wanted me to use 20-50, but i knew that was to thick, and to much parasitic loss, with no lubricity gain.......it runs fine, and 11:07 ET at 120 mph at the track satisfies me nicely.......GREAT VID!!

Tony. thank you for offering these educational moments.

I found and restored an antique Soviet Union KMZ Dnepr military sidecar motorcycle. You can call it the step brother of Ural sidecar motorcycles. It's oil pressure is 6 bar or 86 psi. While I was reading the manual I found the reason it's so high. It's for cooling and lubricating the Pistons because it's designed to operate at idle for extended periods of time. It's an air cooled boxer engine so you would think idling like that at 5km an hour would burn it up. The way it works is high pressure and volume oil is pumped to the crankshaft where it lubricates shell type bearings on the rods but then it sprays out of the bearings and into the back of the Pistons. It also produces a thick mist of oil that lubricants the ball bearings on the crankshaft and camshaft. That slinging oil also lubricates the cam lobes and lifters. Small channels guide oil down the pushrod tube's to lubricate the rocker arms and other valve components. The heads and cylinders have deep cooling fins as well. What's even more interesting is Harley Davidson made 1,000 copy's of them in 1942 and 43 calling them XA models for experimental. They were going to be used in North Africa but by the time the XA's we're finished testing North Africa was won and done.

my 1974 kawi G5 100cc 2 smoker actually "pressure" lubes the crank mains . half goes just past the carb..... the other half drips on the mains OVERKILL for a 100cc smoker that makes 12hp.... . but, ive put 15,000 miles on the rebuild.... and i havent had a break down havent even fouled a spark plug.... (but have replaced it when it wore out) . still starts first kick.... runs SUPER crisp.... throttle response is so good, really easy to rev match shifts up and down . . i just LOVE that bike

TONY, YOU'RE THE MAN. THANKS FOR SHARING.

Well your video might be a year old but it certainly answers a lot of questions that I have wondered about for more than 50 years! In the 70's I used to build high revving high hp straight 6's. They often hit 8k Rpm I never went to route of high volume high pressure oil pumps cos I just didn't see the need. That's not to say I really understood, I just chose not to. Who would have guessed.

Great explanation, thanks for posting.

We ran circle track dirt posse car back in the late 80s. 383 mopar 30 over 10.5:1 popup TRW pistons, 8 bolt truck crank, aluminum flywheel on methanol. Holley alcohol carb 830CFM. Solid lifter with adjustable rockers, edelbrok torqer manifold, 1 7/8" headers with spiral wound half muflers. To the point, we ran loose clearances with a high pressure, high volume oil pump and Valvoline racing 50 WT oil. We'd see 60PSI idoling and a bit higher hot at 6,800 RPM. It had a grunt sound like it was trying to shotput the car down the straights. Good times.

I learned something today, thank you

This video is loaded with info!! Thanks so much!

Uncle Tony and Uncle Ted are my favorite Uncle’s!!!

If you've ever used an electric drill to prime an engine you can really Feel the resistance of moving the oil. Great Video..

My 408 Cleveland hydraulic lifter setup has 2thou clearances throughout, it runs a Mellings hv pump using Brad Penn 20/50 and it achieves around 50 pounds at idle (warm) peaking at around 80 pounds at 6000rpm. It was built with a mild street aim with lower maintenance in mind. It runs most of the internal goodies with 245cfm rated 2V closed chamber heads limiting a couple of factors, home built 14yrs ago, on the dyno it made 250rwkw and still runs just the same today as I've only put around 14k miles on it since the build and it is maintained religiously. Your not wrong about parasitic loss though, it can quickly add up all over the place. It runs a large 7 blade fan surrounded with a good quality shroud, 1 big loss right there but I KNOW it's always doing its job, I carry a spare belt atleast. It's all horses for courses I guess, and what fits the budget at times. Great video once again Tony 🇦🇺👍

Thanks Tony! Super information, great video!

Most of us already know this but I just purchased a pinned distributor shaft right from Mopar performance. It's amazing they relied on a press fit gear.

Needed this information. Thank you Tony!!!

I love all these tips....this one I new not because I am a great mechanic but because I have a memory like an elephant. Its also common sense. At some point in going to build my very first 383 stroker for my square body suburban. People swear I won't be able to get fuel economy out of it but I'm doing enouph research first I will prove em wrong! I wish I lived close, I was like your favorite nephew and you wanted to give me advice on my build......Lol

Saw my old buddy Ron Ward in one of your videos. Great guy. Many of us miss the old days!!!!!!!!!!!!!!!!!

completely makes sense!!! definitely got some outa that, thanks!

Love ur abundance of knowledge, Thanks a lot for sharing.

I have a 1964 Galaxie 500 with the 352 FE motor. When I rebuilt the motor 30 years ago the rebuilder said to use 10w 40 as a break in then 20w 50. He has retired and closed up shop. I talked to another mechanic and he also said to use 20w 50. Although the owners manual from 1964 says to use 10w 30. I use the 20w 50 but change it every year even if I only put 500 miles on the car. I also add 1/2 qut of marvel mystery oil.

Your correct sir, no one covers this. Thanks for the information.

Awesome video, your full of very useful wisdom and information. To me the oil pump is the heart of an engine. And the oil pump plus the oil system is over looked when modifying a vehicle,

Really good, and not talked about much. Remember talking to the Craftsman Series Truck Racers/Drivers in the pits, and I asked about the breathers on their crankcases and a few of them went to explain that they were playing an oil pressure game at (I think) they said @ 8500RPMS; the take away for me at least in this capacity seemed to be less is more.

Great information! Very well explained! Thank You!

Just what I needed to know. Thanks again UT.

Definitely appreciate all your videos always helpful

Great info Tony!!!

Man utg you hit the nail right on the head with this video awesome job explaining this

I have an early HD Panhead and the service manual reads oil pressure 35psi, 20 psi at 20 MPH. It is adjustable. Timing case gears are bushed. The main shaft is roller bearings which are "air cooled". The rod big end is roller bearings that are oil cooled. The rods fling oil all over and need good pressure/flow to not over heat. Thinner oil does ccol better.

Tony !!!! you are giving all the secrets away!!!!

Great content. Spot on

Happy Thanksgiving Tony. I love your channel.

I use to sit in smokey yunick office when my old man use to talk to him. U were a big help I have a 300 6 banger at idle is has about 7 psi it has 210000 on it

Because oil likes to cling to itself and metal the faster a shaft turns inside a bearing the more oil it will pull into the bearing, yea it draws itself in. There are some of the new design engines that need some of that pressure to spray sufficient oil out piston cooling jets and maintain pressure on cam chain tensioners but even then it's not an excessive amount. I remember back in the 80's, Cummins changed there strategy on the 855 diesel in over the road trucks. They went from typical 65 to 75 PIS oil pressure to 40 Psi. Reduced oil shear, and parasitic load a lot. Mainly freaked out experienced drivers but it really worked. We had a small Detroit engine in a truck that at overhaul it got the incorrect spring in bypass. It had about 15 PSI more pressure than it was supposed to. After about 15 to 20 miles running down the road it would develop low oil pressure. Seems the excess pressure caused the oil to get hot from shear then it would be to thin, changed spring to reduce pressure and pressure drop went away. Love your stuff Tony and I'm not even a Mopar fan. Keep up the good work.

Thank you UT!

Thanks for the great analysis.

3:12 I remember going through A school in the Navy; was taught oil has three functions; it cools, flushes, and lubricates.

I've always heard a minimum of 7 psi/1000 rpm too so I always assumed that was ok. The only time I've ever used a high pressure pump is on race only engines. High volume pumps can actually damage an engine if you run a stock oil pan. There's a chance that they can empty the sump and starve the pickup before enough oil has drained back down. I do disassemble the pump (new or used) and check the clearances as well as making sure that the mating surfaces are flat when I do any build.

Damn Tony, I think this is the best video you have ever done. Bad ass!

Another excellent lesson Uncle Tony Cheers & stay safe😊

I have shown people about this with our dirt late model dry sump pump. It has an adjustment screw. When your idling at 900 rpm with 50psi oil pressure and you turn the psi down to 10psi and your rpm goes to 1200 with no carb adjustment they see the light real quick. We run .0025 to .003 for our rods and mains we run restricted oil passages to the lifters because they are solid rollers...

Thank you for the knowledge.

Great info! We novices always think more is better and put a high volume pump on a stock rebuild....

This video is worth a like for sure