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ISO 68 question
- Thread starter dpb
- Start date
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- Feb 2, 2013
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yes. there are many oil types in ISO68.
hydraulic fluid, anti-wear hydraulic fluid, way lubricant, engine oil, spindle oil,aviation hydraulic fluid, etc are all types of oil available in ISO68, all for different purposes.
it seems to me, that the oil with the least number of additives, would have the most capillary action.
my thought being, a smaller molecule can pass through smaller holes.
this of course would be in disregard to an additive to reduce viscosity.
hydraulic fluid, anti-wear hydraulic fluid, way lubricant, engine oil, spindle oil,aviation hydraulic fluid, etc are all types of oil available in ISO68, all for different purposes.
it seems to me, that the oil with the least number of additives, would have the most capillary action.
my thought being, a smaller molecule can pass through smaller holes.
this of course would be in disregard to an additive to reduce viscosity.
I changed the oil in my PM1440gt from whatever the factory used, to Chevron R&O 68. Matt recommends Mobil DTE 68, but said the R&O ought to be fine. I noticed a leak around the left end of the spindle, shortly after, as well as seepage up around the filler plug, regardless of tightness. I’m trying to figure out if this is a coincidence, or if I need to dump the R&O for DTE.
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Saying ISO 68 is like saying SAE 20. It is only giving the viscosity of the oil, under two different standards systems. They tell you nothing else about the oil beyond viscosity.
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- Jul 2, 2014
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You are still trying to stop the leak on your lathe apron. Viscosity tells everything there is to know about how easily oil flows through small passages, based on that number alone. That is probably not a worthwhile path to go down to try to stop your leak. Thick and thin liquids will all leak, just at different rates. If there is a hole, oil will flow through it.
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Per the oil description, Chevron R&O Oil is designed for use in many applications that require protection against rust and oxidation, but do not require anti-wear or extreme pressure additives. It may be used for lightly loaded plain and anti-friction bearings, electric motors, machine tools, air compressors, and circulating systems that require rust and oxidation inhibited oil. FS Turbine R&O Hydraulic Fluid can also be used as a gear oil where API GL-1 service is specified. It is widely used where non-detergent motor oils (API SA) are specified.
GL1 oil is the lowest level of performance and is typically used in vintage transmissions and simple lightly loaded bearings. It is very similar to engine oil, having a very low additive content, but is available in much higher (thicker) viscosities to suit gearboxes with unsophisticated oil seals. So technically it should be acceptable substitute, but have a less robust additive package than typical gear oil.
Chevron R&O Oil is specified as a turbine oil, so the oil hydrocarbon chain size may differ from other oils. So something like a synthetic oil is more homogeneous as far as molecular size vs, standard oils. I recall one of the issues with synthetic oils when they first came out, is that you would see more leaking past seals in older cars. This typically wasn't because of damage to the seal, but the smaller molecule would seep past worn/poor seals. Thee are different opinions as to the effect of synthetic oils on some older seals. Swelling can occur from penetration/absorption of the oil into the seal, shrinkage from extraction of solubles from the seal. The effect on seals is dependent on the molecular size/type, larger, the larger more branched chain and non-polar cause less changes to seals. Non-synthetic oils are typically a heterogeneous mix of oils to give a specific viscosity, I would suspect this may be the case using a turbine R&O oil which is designed for very high operating RPM, which would typically be oil with a more narrow molecular structure variation similar to synthetics, although molecularity quite different. This could cause more seepage.
https://www.machinerylubrication.com/Read/30161/understanding-synthetics-differences
Since a gallon of Mobil DTE gear oil is inexpensive, it may be worthwhile to switch and see if there is a difference. You can use some Teflon tape around the threads of the upper fill plug and also the drain plug.
GL1 oil is the lowest level of performance and is typically used in vintage transmissions and simple lightly loaded bearings. It is very similar to engine oil, having a very low additive content, but is available in much higher (thicker) viscosities to suit gearboxes with unsophisticated oil seals. So technically it should be acceptable substitute, but have a less robust additive package than typical gear oil.
Chevron R&O Oil is specified as a turbine oil, so the oil hydrocarbon chain size may differ from other oils. So something like a synthetic oil is more homogeneous as far as molecular size vs, standard oils. I recall one of the issues with synthetic oils when they first came out, is that you would see more leaking past seals in older cars. This typically wasn't because of damage to the seal, but the smaller molecule would seep past worn/poor seals. Thee are different opinions as to the effect of synthetic oils on some older seals. Swelling can occur from penetration/absorption of the oil into the seal, shrinkage from extraction of solubles from the seal. The effect on seals is dependent on the molecular size/type, larger, the larger more branched chain and non-polar cause less changes to seals. Non-synthetic oils are typically a heterogeneous mix of oils to give a specific viscosity, I would suspect this may be the case using a turbine R&O oil which is designed for very high operating RPM, which would typically be oil with a more narrow molecular structure variation similar to synthetics, although molecularity quite different. This could cause more seepage.
https://www.machinerylubrication.com/Read/30161/understanding-synthetics-differences
Since a gallon of Mobil DTE gear oil is inexpensive, it may be worthwhile to switch and see if there is a difference. You can use some Teflon tape around the threads of the upper fill plug and also the drain plug.
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