Iso Vs Sae

[mksj]

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

Chinese gear head mill with stock oil, I went to a synthetic gear head oil by Amsoil. The difference was significant.

Please show me one lathe or mill manufacture that states motor oil can be substituted for gear oil in their machine. Moisture and condensation is always an issue, especially in more humid climates. Many machines have a crankcase breather tube, so they are constantly pulsating air into the gear case.

When you drain the oil, you often find a lot of particulates in the oil and it can be quite dirty, so if you don't mind having all this stuff floating in the oil, then go for the detergent oil. There are plenty of testimonials about the use of motor oils in lathes mills, etc. both pro and con. The There is enough reports in other forums about the machine running hotter (due to increase frictional shear) with the motor oil, that I still think one should stick with the proper recommended oil, as opposed to saving a dollar or two here or there. The other factor, just like in motors, change you oil at the recommended intervals.

I still disagree on the use of motor oil in gearheads, because the motor oil viscosity is designed around the operating temperatures of motors, gear oils are designed around much lower operating temperatures (usually 40C). The viscosity difference can be very significant. Putting 10W motor oil in your lathe might be closer to putting ISO100 at the operating temperature in a lathe. The difference in viscosity for a motor oil at the two operating temperatures is about 3X. Per Amsoil blurb: "Because an internal combustion engine has an oil pump and lubricates the bearings with a hydrodynamic film, extreme-pressure additives such as those used in gear oils are not necessary."
http://www.amsoil.com/newsstand/auto-and-light-truck/articles/dont-forget-the-gear-oil/?zo=34396


Gearhead oil was black and full of metal particles after 1 year.

 

[Steve Shannon]

The South Bend Lathe Company, in the booklet "How to Run a Shaper", very specifically says "Do not use automobile engine oil or any oil which may contain a detergent" in the oil reservoir.
Grit and water are both byproducts of internal combustion, which of course does not happen in a lathe, but a certain amount of fine metallic particles would not surprise me just from wear. If your lathe is subjected to heating and cooling cycles and your air has any humidity at all you could have condensation as well. If so, they would remain suspended in a detergent oil, but not in a machine oil.
Amsoil has a page that briefly discusses the differences between engine oil and gear oil, which points out that gear oil and engine oil each have different additives and why.
http://www.amsoil.com/newsstand/auto-and-light-truck/articles/dont-forget-the-gear-oil/?zo=34396


Steve Shannon, P.E.

 

[Tozguy]

This is a quote from the Amsoil link mentionned above:
'Motor oil contains additives such as detergents and dispersants to combat byproduct chemicals from gasoline or diesel ignition.'
Where is a reliable claim that detergent oils hold metallic particles in suspension more than non detergent oils? As a matter of fact, several of my cars and motorcycles have had a magnetic drain plug too. Why?

If your machine has a condensation problem then what happens to the water if the oil doesn't disperse it?

If your machine is producing metallic particles in the gear box and using non-detergent oils will solve the problem then you are home free.

I am not advocating using the any viscosity oil in any type of gearbox. If your oil needs changing for any reason then change it. If a manufacturer specifies against using detergent oil then don't use them.

I think that Bob kept it simple in post No.4

 

[Bob Korves]

My post #4 was a warning. You do not want to use vegetable oil of the correct viscosity in your machines unless it is specified. RTFM. Use the recommended oil. Why do we think we need to outguess the designers and builders of our machines? I will not necessarily follow brand name recommendations, but will use the correct type and viscosity of oil specified in any machine I am servicing, and at the recommended intervals. I have never had an oil problem, corrosion problem, or excessive wear problem. Coincidenza?

 

[mksj]

Please show me one lathe or mill manufacture that states motor oil can be substituted for gear oil in their machine.

An apple is not an orange just because it is round.
If you read the Jet lathe manuals they specifically state do not use detergent oils.
If you read the Grizzly lathe manuals they specifically state do not use detergent oils, and direct communication states concern to seals when detergent oils are used.
If you read the Clausing lathe manuals they specifically state do not use detergent oils.
If you read the SB lathe manuals they specifically state do not use detergent oils.
These lathe manuals specify use of gear oils not motor oils
The viscosity index for ISO gear oils is based on 40C, SAE motor oils is based 100C
The friction modifiers, foaming properties and rust corrosion properties are very different
The Amsoil blub on gear oil specifically states their formulation and properties is very different then motor oil. The title is
"Gear Oil and Motor Oil Are Not the Same"