Motor Oil ?
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Motor Oil ?

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    Sit N' Spin Jetaholic's Avatar
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    Default Motor Oil ?

    In researching information I've gathered some interesting info regarding motor oil. From the info I gathered, this is what I'm getting from it.

    Pressure is an opposition to flow

    Thicker oil resists flow more than a thinner oil (easier to push a thinner oil than a thicker one)

    Better oil FLOW = better lubrication = better cooling

    Oil pumps DO NOT create pressure, they create oil FLOW. The resistance to flow that the thickness of the oil + the size of the passages provides creates the pressure. The bypass spring governs how high this pressure can increase.

    An increase in flow will cause an increase in pressure. Pressure will only increase to the point at which the pump bypass allows it to. Oil pressure can only be increased by an increase in flow. Once pressure rises enough to open the bypass, oil flow through the engine will no longer increase with RPM. The pump will still pump more oil volume with an RPM increase, however the increased flow of the pump is bypassing instead of providing an increase in flow through the engine, indicated by the pressure holding steady as the RPMs increase. Having said that, it would make sense to run the thinnest oil possible that will hit the bypass at your max RPM yet still maintain a minimum of 10 PSI per 1,000 RPM.

    Running too thick of an oil will cause it to overheat at max RPM. This would be indicated by pressure dropping at max RPM. The pressure drop is indicating that the oil is reaching a temperature at which it flows better, however this temperature is so hot that it overheats the oil and it simply cannot cool or lubricae the parts. By running a thinner oil, the oil can flow better at a lower temperature than a thicker oil can, and therefore increase cooling at a lower temperature. Due to the lower temperature, the oil will not lose its viscosity like the thicker oil did.

    Engines with looser clearances will benefit from running a thinner oil. With the increased amount of space between the parts, thinner oil can fill those spaces quicker than a thicker oil can due to the fact that it flows better than the thicker oil at a lower temperature.

    Pressure should increase with RPM, indicating that flow is also increasing with RPM (increase in flow causes increase in pressure). If pressure is NOT increasing with RPM, this means that flow is not increasing with RPM since an increase in flow causes an increase in pressure.

    Example - You have an engine with an oil pump that bypasses at 50 PSI. An oil pump at 1,000 RPM idle is spinning at 500 RPM. At 500 RPM, it can only push enough oil through the engine to lubricate it at an idle.

    Let's say that by 1500 RPM, you're already hitting the bypass. This means that the oil pump will bypass all additional oil flow past this RPM and it will only flow enough oil through the engine to lubricate the engine at 1500 RPM because it is bypassing the rest of it. Flow can no longer increase with RPM at this point, which causes the pressure to hold constant. Since you're only flowing enough oil to lubricate the engine at 1500 RPM, any increase in engine speed will overheat the oil, causing it to thin out, which will cause it to flow better, but the oil is so hot that it cannot properly lubricate and cool at this point.

    Example 2 - You have an engine with the thinnest oil that will provide a minimum of 10 PSI per 1,000 RPM. You idle at say...15 PSI. The pump will not bypass until 60 PSI. With this setup, flow will increase with RPM because the bypass is far from being open, so the oil has no choice but to flow through the engine. As flow increases, pressure will increase as well until it hits the bypass. In an ideal situation, this would not happen until the engine reaches max RPM.

    Pressure that increases with RPM indicates an increase in flow. High pressure readings that hold steady as RPMs increase indicate that you're running too thick an oil for it to flow properly.

    The idea behind oil pressure is to run the thinnest oil that will provide a minimum of 10PSI of pressure at 1,000 RPM, yet will not pop the bypass open until at or just before you hit max RPM. Pressure at the bypass opening point should be a minimum of 10 PSI per 1,000 RPM (at 6,000 RPM, it should be no lower than 60 PSI).

    The thickness of the oil is NOT what provides the "cushion" between parts. Oil PRESSURE is what does this.

    Am I wrong in thinking this?
    Last edited by Jetaholic; 07-24-2009 at 05:33 PM.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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    Super Moderator HammerDown's Avatar
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    Hammer pulling up a chair and getting some...
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    What if the "bypass" is Blocked? And in a jet boat? That might be cool in a car.... Something that isn't running at high rpm But I am not buying it! jmo

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    21 Daytona Outlaw's Avatar
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    Quote Originally Posted by HammerDown View Post
    Hammer pulling up a chair and getting some...
    Please pass some this way
    #55

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    Sit N' Spin Jetaholic's Avatar
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    I have no idea why the popcorn...I presented this as a question. This is based on an article I read and the points mentioned above is how I personally interpreted the article, and the question was if my interpretation of it is wrong.
    Last edited by Jetaholic; 07-24-2009 at 06:30 PM.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

  8. #6
    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by Jetaholic View Post
    .../
    The thickness of the oil is NOT what provides the "cushion" between parts. Oil PRESSURE is what does this.

    Am I wrong in thinking this?
    I'm with ya but, I feel 'film strength' also plays a major part in protecting too.

    *I tried the 15/40 Rotella (no oil cooler) during a simple 3500 rpm cruise I saw the oil psi get lower, and lower, and lower. It stopped at 48 psi @ around 220 degrees >no oil cooler.

    I'm giving 20/50 another chance but feel a small oil cooler is still in my future.

    I've been all about straight wt 40 or 50...but .002 rods and .0025/.0028 mains tell me different.
    Thicker oil wont flow as well thus will get hotter spending more time on 'hot' parts but where's the 'film/sheer' strength of thin oils?

    *Back to the Diesel 15/40...my little mind was thinking about this...most if not all Diesel engines make their power down low...1800-2500 RPM not really enough RPM to hammer the death out of a oil. But in my boat, crusing at 3500-4500 I don't feel the Diesel blend is the answer...so, some add "Oil Stabilizers" like Lucas, STP, Hi-TacK etc to build up the oil's film strength and make it less subject to sheering and breaking down.

    Soooo with that in mind, why not use a lighter straight wt and warm it up a bit longer???

    I would feel better with the thinner oils (if) a oil cooler was being used.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by Jetaholic View Post
    I have no idea why the popcorn....
    The "popcorn" was NOT intended as a insult to your topic, I think it will be a darn good thread! I'll be


    sitting here, eating my reading every post
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    21 Daytona Outlaw's Avatar
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    hammer why a straight weight? just curious, oh and I love the corn
    #55

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    Sit N' Spin Jetaholic's Avatar
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    Another thing I got from the article was that the mineral based multi-vis oils are made from a straight weight form of the smaller number in the multi-vis rating, but have viscosity modifers in them that don't allow it to get thinner than what a straight weight version of the bigger number would be at operating temp (i.e. a 20-50 multivis is made from a 20 weight oil and is the same viscosity of a 20 weight oil when cooled, but has viscosity modifiers that won't allow it to get any thinner than what a straight 50 weight oil would be at normal operating temperature). The problem that multi-vis oils were made to solve was not the thinning when hot, but rather the thickening when cooled (straight weight oils are much thicker when the engine is cold and take longer to come up to temperature and will not flow properly until at or close to operating temp).

    However, synthetic multi-vis oils are made from the higher number in the rating (i.e. a 20-50 synthetic is made from a 50 weight oil), but naturally they don't thicken up nearly as much as a mineral based straight weight oil would upon cooling and therefore don't need the viscosity modifiers.

    Having said that, in theory a 20-50 should perform exactly like a straight 50 weight oil would at temperature, but only thicken as much as a 20 weight oil would upon cooling. The multi-vis oils also don't take as long to come up to temperature as a straight weight oil would.

    On the mineral based multi-vis oils, using 20-50 as an example, overtime you will lose the viscosity modifiers and the oil will be just like having a straight 20 weight once those are gone. Whereas with a synthetic oil there are no modifiers so there's nothing to lose...plus they're made from the a straight weight version of the bigger number in the rating anyway (20-50 synthetic is made from a 50 weight oil).
    Last edited by Jetaholic; 07-24-2009 at 06:50 PM.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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    BTC cardcarrying member SuperSoaker's Avatar
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    Quote Originally Posted by hammerdown View Post
    i think it will be a darn good thread! I'll be
    sitting here, eating my reading every post )thumbsup
    x2

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    New here Beer:30's Avatar
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    Seems pretty accurate. I agree with thinner oil filling voids. Alot of peeps think you need thick oil for "loose" motors. Personally, I would see more volume of thinner oil packed into a clearance would be much better than less amount of thick oil. Thinner oil will also get there quicker, which is not theory - just physics.

    Running 10/30 Mobil-1, I feel is more than adequate for my 496. It has an oil cooler, so temps are always stable. And, since 0w Mobil-1 is good enough for NASCAR motors, I don't see any reason to spin more than a 30w oil.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    Quote Originally Posted by HammerDown View Post
    I'm with ya but, I feel 'film strength' also plays a major part in protecting too.

    *I tried the 15/40 Rotella (no oil cooler) during a simple 3500 rpm cruise I saw the oil psi get lower, and lower, and lower. It stopped at 48 psi @ around 220 degrees >no oil cooler.

    I'm giving 20/50 another chance but feel a small oil cooler is still in my future.

    I've been all about straight wt 40 or 50...but .002 rods and .0025/.0028 mains tell me different.
    Thicker oil wont flow as well thus will get hotter spending more time on 'hot' parts but where's the 'film/sheer' strength of thin oils?

    *Back to the Diesel 15/40...my little mind was thinking about this...most if not all Diesel engines make their power down low...1800-2500 RPM not really enough RPM to hammer the death out of a oil. But in my boat, crusing at 3500-4500 I don't feel the Diesel blend is the answer...so, some add "Oil Stabilizers" like Lucas, STP, Hi-TacK etc to build up the oil's film strength and make it less subject to sheering and breaking down.

    Soooo with that in mind, why not use a lighter straight wt and warm it up a bit longer???

    I would feel better with the thinner oils (if) a oil cooler was being used.
    Well HD, I can tell you that, for 6 years now, I have run Synthetic 10w-50, with nothing added to it.
    454 Chevy
    STOCK non-high volume Melling oil pump.
    No modifications to pump bypass or block.
    .0025" main and rod bearing clearances.
    5 quart pan, 2-quart K&N oil filter.
    The longest WFO run I have ever made, was about 8 miles, 5,000RPM at the time (2007).
    Cruising is generally 3500-4,000rpm, depending on water conditions.
    No oil cooler, of any size.
    Longest cruising trip I have ever made was 20 miles, 1 way. Topped up fuel and cruised back.

    I get 58psi cold idle leaving the trailer.
    I get 58psi, WFO @ 5400RPM.
    I get no loss of oil pressure over that 8-mile run I made.
    Also no loss on shorter runs, of 3 to 5 miles, 5400RPM now, which happen regularly.
    I get 23psi hot idle oil pressure.
    Anything above 2,000RPM or so, I am above 40psi.

    That 8-mile run was not made right off the trailer, but after a couple hours on the water, things were well warmed up to start with.
    A friend was driving, I was watching the gauges (especially the GAS gauge LOL).
    Oil pressure was rock solid.
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    Senior Member earlbrown's Avatar
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    Here you go. Plenty of stuff to read for a viscosity overload...


    http://ferrarichat.com/forum/showthread.php?t=136052

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    Quote Originally Posted by earlbrown View Post
    Here you go. Plenty of stuff to read for a viscosity overload...


    http://ferrarichat.com/forum/showthread.php?t=136052

    Still reading it, but very down-to-earth article.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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