Safe to switch? 10w-60 to 0w-20 BMW M50tu
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Originally Posted By: thehomelessone
Currently running 10w-60, still burning oil pretty fast. Want to try Amtecol 9000N 0w-20. My gearing is fairly short so I'm turning almost 4k rpm on the highway, barely getting 21mpg, curious to see how much 0w-20 will help. Was also thinking, if the rings are worn, shouldn't a thinner oil be easier for the oil rings to wipe off the bore?
Most make pretty good arguments against using thin oils in motors not made for them, but I still want to hear what others think. I read something a while ago, that the bearings fill with oil, and because they're spinning so fast and oil is constantly being replenished, it's capable of sustaining much higher pressures. So thin or thick oil should be fine.
Worst case, I destroy my engine, m50's are everywhere for cheap, still hoping it doesn't happen haha
Why are you playing with viscosities when you don't even know what is wrong with your engine?
Get a wet and dry compression check done on the cylinders to ascertain if you do even have piston ring wear.
It's the oil that makes the seal between the rings and the cylinder so if your rings are worn and you go too thin then more oil will escape past the rings into the combustion chamber.
"The bearings fill with oil because they're spinning so fast" is called hydrodynamic lubrication, you do not have this in your engine, you have hydrostatic lubrication which is bearings operating on a bed of pressure fed oil fed from the oil pump.
Put the manufacturer recommended oil in and get your engine checked.
Currently running 10w-60, still burning oil pretty fast. Want to try Amtecol 9000N 0w-20. My gearing is fairly short so I'm turning almost 4k rpm on the highway, barely getting 21mpg, curious to see how much 0w-20 will help. Was also thinking, if the rings are worn, shouldn't a thinner oil be easier for the oil rings to wipe off the bore?
Most make pretty good arguments against using thin oils in motors not made for them, but I still want to hear what others think. I read something a while ago, that the bearings fill with oil, and because they're spinning so fast and oil is constantly being replenished, it's capable of sustaining much higher pressures. So thin or thick oil should be fine.
Worst case, I destroy my engine, m50's are everywhere for cheap, still hoping it doesn't happen haha
Why are you playing with viscosities when you don't even know what is wrong with your engine?
Get a wet and dry compression check done on the cylinders to ascertain if you do even have piston ring wear.
It's the oil that makes the seal between the rings and the cylinder so if your rings are worn and you go too thin then more oil will escape past the rings into the combustion chamber.
"The bearings fill with oil because they're spinning so fast" is called hydrodynamic lubrication, you do not have this in your engine, you have hydrostatic lubrication which is bearings operating on a bed of pressure fed oil fed from the oil pump.
Put the manufacturer recommended oil in and get your engine checked.
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Maybe, they sound like hydrostatic rather than hydrodynamic bearings though
Fluid bearings are bearings that support their loads solely on a thin layer of liquid or gas.
They can be broadly classified into two types: fluid dynamic bearings and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and the pressurization is done by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces.
Fluid bearings use a thin layer of liquid or gas fluid between the bearing faces, typically sealed around or under the rotating shaft.
There are two principal ways of getting the fluid into the bearing:
In fluid static, hydrostatic and many gas or air bearings, the fluid is pumped in through an orifice or through a porous material.
In fluid-dynamic bearings, the bearing rotation sucks the fluid on to the inner surface of the bearing, forming a lubricating wedge under or around the shaft.
Hydrostatic bearings rely on an external pump. The power required by that pump contributes to system energy loss, just as bearing friction otherwise would. Better seals can reduce leak rates and pumping power, but may increase friction.
Hydrodynamic bearings rely on bearing motion to suck fluid into the bearing, and may have high friction and short life at speeds lower than design, or during starts and stops. An external pump or secondary bearing may be used for startup and shutdown to prevent damage to the hydrodynamic bearing. A secondary bearing may have high friction and short operating life, but good overall service life if bearing starts and stops are infrequent
Fluid bearings are bearings that support their loads solely on a thin layer of liquid or gas.
They can be broadly classified into two types: fluid dynamic bearings and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and the pressurization is done by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces.
Fluid bearings use a thin layer of liquid or gas fluid between the bearing faces, typically sealed around or under the rotating shaft.
There are two principal ways of getting the fluid into the bearing:
In fluid static, hydrostatic and many gas or air bearings, the fluid is pumped in through an orifice or through a porous material.
In fluid-dynamic bearings, the bearing rotation sucks the fluid on to the inner surface of the bearing, forming a lubricating wedge under or around the shaft.
Hydrostatic bearings rely on an external pump. The power required by that pump contributes to system energy loss, just as bearing friction otherwise would. Better seals can reduce leak rates and pumping power, but may increase friction.
Hydrodynamic bearings rely on bearing motion to suck fluid into the bearing, and may have high friction and short life at speeds lower than design, or during starts and stops. An external pump or secondary bearing may be used for startup and shutdown to prevent damage to the hydrodynamic bearing. A secondary bearing may have high friction and short operating life, but good overall service life if bearing starts and stops are infrequent
hydro "static" bearings rely on the pressure of a pump to keep the parts separated...they will provide that part separation at zero surface speed differential, based solely on the pressure of the lubricant keeping the parts separate.
Hydro "dynamic" bearings use the relative motion of the two surfaces to be separated to create the high pressure between them.
Your oil pump is simply there to provide the oil to the bearing, which creates it's own separation pressure...the pressure of the oil in the hydrodynamic film can be any tens of times the oil supply pressure...in fact, the oil supply pressure local to the bearing can be sub-atmospheric, as the bearing will suck it's own oil from the galleries...like I said, the oil pump is the means of keeping oil to the bearings...not what keeps them separated.
Take a turbine bearing (have designed a few, and a few lubrication systems/mods)...
* there is a hydrostatic port at the 6:00 position, which is fed 3000psi oil to lift the shaft, and allow it to roll.
* There is an oil supply (usually at 9:00) where the oil is fed at 30psi, but goes -ve at speed as the low pressure area in the bearing sucks oil in)...it provides oil, in volume.
* At speed, the spinning shaft in the bearing creates it's own pressure. This is the oil "wedge" that we talk about. It's 150psi or thereabouts, and keeps the parts from touching.
Motor vehicle journal bearings are clearly hydrodynamic, as the pressure is oil supply only.
If you don't believe, then look where the oil gallery is on a main bearing, and where the applied 50psi or thereabouts is...it's not "lifting" the bearing off the shell, it's jamming them together if there's any hydrostatic forces at play.
Hydro "dynamic" bearings use the relative motion of the two surfaces to be separated to create the high pressure between them.
Your oil pump is simply there to provide the oil to the bearing, which creates it's own separation pressure...the pressure of the oil in the hydrodynamic film can be any tens of times the oil supply pressure...in fact, the oil supply pressure local to the bearing can be sub-atmospheric, as the bearing will suck it's own oil from the galleries...like I said, the oil pump is the means of keeping oil to the bearings...not what keeps them separated.
Take a turbine bearing (have designed a few, and a few lubrication systems/mods)...
* there is a hydrostatic port at the 6:00 position, which is fed 3000psi oil to lift the shaft, and allow it to roll.
* There is an oil supply (usually at 9:00) where the oil is fed at 30psi, but goes -ve at speed as the low pressure area in the bearing sucks oil in)...it provides oil, in volume.
* At speed, the spinning shaft in the bearing creates it's own pressure. This is the oil "wedge" that we talk about. It's 150psi or thereabouts, and keeps the parts from touching.
Motor vehicle journal bearings are clearly hydrodynamic, as the pressure is oil supply only.
If you don't believe, then look where the oil gallery is on a main bearing, and where the applied 50psi or thereabouts is...it's not "lifting" the bearing off the shell, it's jamming them together if there's any hydrostatic forces at play.
I see now said the blind man
apologies for any ruffled feathers
I knew that oil pressure was created via resistance to the oil supply from the pump but always thought, as you cannot compress a liquid, that it was this pressure (25psi - 75psi) that kept the bearings apart.
apologies for any ruffled feathers
I knew that oil pressure was created via resistance to the oil supply from the pump but always thought, as you cannot compress a liquid, that it was this pressure (25psi - 75psi) that kept the bearings apart.
Originally Posted By: riggaz
I see now said the blind man
apologies for any ruffled feathers
I knew that oil pressure was created via resistance to the oil supply from the pump but always thought, as you cannot compress a liquid, that it was this pressure (25psi - 75psi) that kept the bearings apart.
All good
I see now said the blind man
apologies for any ruffled feathers
I knew that oil pressure was created via resistance to the oil supply from the pump but always thought, as you cannot compress a liquid, that it was this pressure (25psi - 75psi) that kept the bearings apart.
All good
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