Iso Vs Sae

[planeflyer21]

I see lots of questions on here about "What oil do I use?" and lots of references to the preferred ISO oil types.

Found this page showing ISO types and their SAE equivalents:
http://www.engineeringtoolbox.com/iso-grade-oil-d_1207.html

 

[British Steel]

Thanks Jon - doesn't go down to ISO 5 though (my lathe's beverage of choice - and it keeps spilling it, I think it has a drinking problem)

Dave H. (the other one)

 

[Garththomas]

Its interesting that Ive been reading a lot about people using 20wt oil instead of iso68 and didn't know why. duh I am a nube thanks for the post.

 

[Bob Korves]

Note that the ISO index or SAE "weight" is just the viscosity of the oil, it says nothing about anything else. Some additive packages are for gasoline IC engines, some for diesel, some for gearboxes, some for hypoid gear boxes, some for way oil, etc. The same ISO index is not necessarily the same oil for the same application, most likely not unless you are careful. All it tells you is how fast the oil flows through an orifice at a standard temperature, nothing else.

 

[Tozguy]

Most IC engines require detergent in the oil to handle the byproducts of combustion. Detergent is not necessary for a lathe but not harmful either. To my mind, general purpose non-detergent oils in SAE viscosities are perfectly suitable for a lathe. The container might even mention the ISO equivalent.

 

[mksj]

Detergent is not necessary for a lathe but not harmful either.

Usually this is not recommended for machines that do not have pressure lubrication with a filter. The detergent lifts all the particles/moisture and suspends it in the oil where you do not want it, motor oils are designed for different heat ranges, have additive packages, waxes, etc. Any oil will work, it just a matter of how well it work over time under the operating conditions. At the core is getting the correct viscosity specified by the manufacturer and the ambient/operating temperature. Different oils have different additives packs for the particular application, all will lubricate. Since one changes the oil infrequently in machines, for the smaller geared machinery I would use a gear oil as opposed to motor oil , and one that is readily available. There are lots of testimonials about using motor oils in their lathe for 20... years and it worked fine, but motor oils are designed for IC motors. I would not advise using motor oils or limited slip gear oils for small machinery gearheads.

http://www.practicalmachinist.com/vb/general/why-non-detergent-oil-143533/
http://www.chaski.org/homemachinist/viewtopic.php?f=42&t=74083&start=15

 

[Tozguy]

Usually this is not recommended for machines that do not have pressure lubrication with a filter. The detergent lifts all the particles/moisture and suspends it in the oil where you do not want it, motor oils are designed for different heat ranges, have additive packages, waxes, etc. Any oil will work, it just a matter of how well it work over time under the operating conditions. At the core is getting the correct viscosity specified by the manufacturer and the ambient/operating temperature. Different oils have different additives packs for the particular application, all will lubricate. Since one changes the oil infrequently in machines, for the smaller geared machinery I would use a gear oil as opposed to motor oil , and one that is readily available. There are lots of testimonials about using motor oils in their lathe for 20... years and it worked fine, but motor oils are designed for IC motors. I would not advise using motor oils or limited slip gear oils for small machinery gearheads.

http://www.practicalmachinist.com/vb/general/why-non-detergent-oil-143533/
http://www.chaski.org/homemachinist/viewtopic.php?f=42&t=74083&start=15

If you advise against using a detergent engine oil of the recommended viscosity in a lathe gearbox , is it because it will harm the lathe or because it is not your first choice?

 

[mksj]

It is not recommended, there is no definitive answer. I have yet to have come across a lathe manufacture that recommends a detergent oil for a non-pressurized lubrication system system. Motor oils are designed to meet viscosity specifications at operating temperatures that are much higher than you would experience in a lathe, so the effective viscosity could be quite different at lower operating temperatures seen in a lathe. There are anecdotal reports of lathe gear heads getting much hotter with the use of motor oils, most likely this is a viscosity issue. As mentioned, all oils will lubricate, will you see the affect of using motor oil in your lathe in 10-20 years, probably not. That being said, in my gearhead lathe, I picked up about 100 RPM on the top end, the head runs much cooler and I have much less foaming running a high quality gear oil. I guess I just don't follow why one would not use the manufactures recommendations on choosing a lubrication oil for a specific machine.

 

[tq60]

Detergent oils keep things in suspension so the filter gan remove it.

If no filter then it wears out the item.

Use "good" oil in your lawnmower and it does not last as long as the cheap non detergent stuff. ( non filtered ones)

The artifacts settle to the bottom of the pan.

A gear head lathe with just splash lube needs good flowing oil but non detergent type to insure things are not held in suspension to get where it can cause harm.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

 

[Tozguy]

It is not recommended, there is no definitive answer. I have yet to have come across a lathe manufacture that recommends a detergent oil for a non-pressurized lubrication system system. Motor oils are designed to meet viscosity specifications at operating temperatures that are much higher than you would experience in a lathe, so the effective viscosity could be quite different at lower operating temperatures seen in a lathe. There are anecdotal reports of lathe gear heads getting much hotter with the use of motor oils, most likely this is a viscosity issue. As mentioned, all oils will lubricate, will you see the affect of using motor oil in your lathe in 10-20 years, probably not. That being said, in my gearhead lathe, I picked up about 100 RPM on the top end, the head runs much cooler and I have much less foaming running a high quality gear oil. I guess I just don't follow why one would not use the manufactures recommendations on choosing a lubrication oil for a specific machine.

There is no argument about the mental security of following reliable recommendations. I have not seen anyone recommend an IC engine oil as better for a geared lathe than a machine oil is, just that it can be substituted for it. Regarding the contention that detergent oil would keep grit and water in suspension and harm the lathe somehow, it is news to me that my lathe is producing particles and water. If it did I would want to know about it and fix it! I wish people would stop making things up.

What oil were you using before you gained 100 rpm, less foaming and cooler running?

In my case, although my shop is stocked with various engine oils, I bought a pail of ISO32 anti-wear hydraulic oil for my lathe simply because it is less expensive than the engine oils I buy.