Newbie here... Oil and lubrication questions...

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To start off (like I have started my previous threads)... I'm a total novice here!

My lathe manual (or the closest thing I can find to a manual for my lathe) says to use "ISO 68 SAE 20W Bearing and Gear Lubricant" (Grizzly manual, some other very similar import lathe)

So, naturally I scoured the web for what I am looking for, and I think I read too much, because now I'm confused. I opened up McMaster-Carr, which seemed to be a popular place to send folks to buy this sort of stuff, and typed in ISO 68. Everything is fantastic so far, I see "Oil", "Food Grade Oil", "Air Compressor Oil", "Food Grade Air Compressor Oil" (is the compressor food grade, or the oil? What does a cook use an air compressor for?), "Chain and Gear Oil" (AHA!), "Hydraulic Oil", "All-Weather Hydraulic Oil", "Food Grade Hydraulic Oil", "Vacuum Pump Oil", and finally "Way Oil".

https://www.mcmaster.com/#iso-68-oil/=1cyz2uf

So, I looked at the "Chain and Gear Oil", and saw to my dismay that while the ISO number (which I'm still not quite sure what it means) is 68, the SAE number is NOT 20W! It is 75 or 80, except for the itty-bitty quart bottle. On the other hand, I scroll up to the plain "Oil" section, and I've got ISO 68, and SAE 20 (which seems to be what Grizzly called for in the manual, but it isn't "gear oil".

For the purpose of this thread, I'm not interested in "close enough". I'm going to have to buy oil anyway, I might as well get what the manual calls for. Also, I want to know why the SAE numbers for all the oils EXCEPT what I was looking for (gear oil) was what I wanted. If I hadn't read so much, I'd just get it, and never be the wiser (and probably never worry about it, either!)

Also, the manual calls for grease in and around the headstock. Someone told me to use oil instead of grease on the gears. Any ideas what spec. I'm looking for regarding that? (just looking for "close enough" here, because that's the kind of person I really am!)
 
SAE gear oils use a different scale:
https://www.bobistheoilguy.com/viscosity-charts/
Grizzly is leading you astray, with its Chinese lack of understanding of Imperial viscosity standards. You want SAE20 weight or the equivalent ISO68 viscosity. Beyond that, you are looking for oil suitable for gears and bearings, not for internal combustion engines or other non machinery uses. The easiest and best way to find something suitable is to get some ISO68 hydraulic oil from a tractor dealer or machinery oil from a machinery supply company. You need plain oil, not engine oil or others with additives not needed or wanted for simply keeping your bearings and gears lubricated and rust free. You do NOT want detergent oil in a splash lubricated system without a circulating pump and filter.
 
There are a various nomenclature for oils, depending on if is is the US and the rest of the world. In the US there is also the confusion that there is SAE motor oil and SAE gear oil which are completely different. So the chart below gives you the conversion between ISO and SAE, this is only an indication of the viscosity not the other properties of the oil. As a general guidance for mills/lathes/machinery you do not want to use car oils, or gearbox/transmission oils because of the additive packages to these oils.

Typically machinery gearbox oils will be listed as such, they also may be called hydraulic oils and spindle oil depending on the viscosity and properties. If I you look at most newer lathe manuals they usually specify an ISO32 oil for the headstock and an ISO68 for the gearboxes/carriage. On sliding surfaces yo will usually see something like Mobil Vactra #2 (ISO68) oil with tackifiers that make it stick to the metal. So if you looking for machine oils, look at the ISO viscosity number to guide you. The oil properties vary, so the base stock may be very different depending on the application. As you mentioned in a piston compressor, mineral oil is often the base stock, but there are no gears. In a gearbox a different base stock might be used or a different additive package.

So for a machine ISO32 oil yo would want to use something like Mobil DTE 24 Hydraulic oil or Mobil DTE Light Circulation Oil
So for a machine ISO68 oil yo would want to use something like Mobil DTE 26 Hydraulic oil light or Mobil DTE Heavy Medium Circulation Oil
There is a numbered series and a named series, they will both fit you application, from what I have been told the numbered series is designed for high pressures and has a different (more slippery) additive package which may not be as suitable for a wet clutch type of system.
https://www.mobil.com/english-us/industrial/pds/glxxmobil-dte-20-series
https://www.mobil.com/english-us/industrial/pds/glxxmobil-dte-named-series
If you are going to get a Gallon of say Mobile DTE24, 26 and Vactra #2 try Zoro with free shipping. If you sign up for their email they will give you another 15% off

On the open drive gears (transposing gear) I use a highly viscous green impact grease, it is often used on heavy machinery and trailer hitches and will not fling off the gears. Oil will go everywhere and make a mess.

Oil Viscosity Charts.jpg
 
I'd say that recommending grease for change gears that are to be handled is not a good idea; handling them would be messy, it is bad enough with oil! change gears flinging oil off has never been a big problem for me.
 
I much prefer the type of grease I use on the end gears to oil for a number of reasons. I tried different oils and grease, most fling everywhere, make a mess under the belt cover and contaminate the drive belt. On the 1340GT, the end gears will sing pretty bad, the only thing that made a significant improvement was using the high impact grease. The grease is only applied to the gear teeth and stays there, it is semi-transparent and provides a cushioning between the gears when meshing. With Norton gearboxes, you only use the change gear for metric threading, so the situation may be a bit different if you have a small lathe and are frequently changing gears. The lathe manuals I have reviewed, usually state to use a thin coat of heavy grease on the gears and wiping away any excess. The grease I use has a high viscosity and is a clay based, so sticks way better than the something like NLGI 2 (bearing grease) and stays on the gears. I picked it up many years ago, it is similar grease to what is used in impact guns and heavy machinery. But use what works best for your type of machine.

End Gears.jpg
 
I use a NLGI 1 grease (Lubriplate 630-AA), which is fairly soft. I first remove all the old grease, which is easy to do, and then put new grease on with an old toothbrush. I do NOT gob it on, I put just enough to lightly wet _the entire contact surfaces of the teeth 'only'_. There is not enough on there to fling off, only to lubricate. It does not attract swarf and grit, mostly because I leave the cover on and no grit or swarf gets in there. I disengage the gear drive when I do not need it for threading or similar, so the grease lasts a long time. Again, it is easy to clean up with a little solvent on a toothbrush when time to start again with fresh lube. I use less grease to coat all the gear teeth on my 13x40 lathe than the toothpaste I put on my toothbrush to brush my teeth. It takes very little grease to lubricate, anything more just attracts swarf and makes a mess.
 
In my case, my primary lathe is a 19" Regal Leblond; under normal circumstances, I do not need to change end gears, except for cutting odd threads that are not provided for on the change box, like 27 for 1/8" pipe thread, and leads that are faster than can be cut with the standard setup, recently I needed a 1" lead for a double acme thread, not to mention metric threads and diametral pitch leads. I made a set of change gears for the lathe that enables most any lead that can be imagined. It would seem that a sheet metal guard could be made to protect your belts, my lathe has the same basic layout, but have had no problems with the belts. My lathe generally runs at speeds much lower than yours, but I have a two speed motor for a high speed range, that probably has peripheral speeds of the gearing that are not far from yours.
 
SAE gear oils use a different scale:
https://www.bobistheoilguy.com/viscosity-charts/
Grizzly is leading you astray, with its Chinese lack of understanding of Imperial viscosity standards. You want SAE20 weight or the equivalent ISO68 viscosity. Beyond that, you are looking for oil suitable for gears and bearings, not for internal combustion engines or other non machinery uses. The easiest and best way to find something suitable is to get some ISO68 hydraulic oil from a tractor dealer or machinery oil from a machinery supply company. You need plain oil, not engine oil or others with additives not needed or wanted for simply keeping your bearings and gears lubricated and rust free. You do NOT want detergent oil in a splash lubricated system without a circulating pump and filter.

Okay, I'll deal with this post for now...

On the lack of understanding front, I think I have Grizzly beat. Are they leading me astray in their SAE numbers or their ISO numbers? Should I be looking for ISO 68 hydraulic oil or gear oil? On the McMaster page the ISO 68 matches the SAE 20 for the hydraulic oil, but ISO 68 is SAE 75 (or so) for the available gear oil. Am I looking for ISO 68 / SAE 75 gear oil or ISO 68 / SAE 20 hydraulic oil? Or, are these both the same?

I've seen some of your other posts before, and I'm guessing that you are the resident oil expert here, so I'm hoping I'm understandable!

I'll deal with the grease/oil on the gears in/near the headstock after I get this figured out...
 
Okay, I'll deal with this post for now...

On the lack of understanding front, I think I have Grizzly beat. Are they leading me astray in their SAE numbers or their ISO numbers? Should I be looking for ISO 68 hydraulic oil or gear oil? On the McMaster page the ISO 68 matches the SAE 20 for the hydraulic oil, but ISO 68 is SAE 75 (or so) for the available gear oil. Am I looking for ISO 68 / SAE 75 gear oil or ISO 68 / SAE 20 hydraulic oil? Or, are these both the same?
The SAE gear oils you will likely find will be for automotive transmissions and especially hypoid geared differentials. They have high pressure additives (sulfur) which will eat yellow metals (bronze, brass, copper, etc.) Do not use those oils in your lathe. Hydraulic oil is fine and inexpensive, available in most cities and even in smaller towns in farm country. Some hydraulic oil is labeled "AW" like AW68 for your headstock. The AW stands for 'anti wear' additives having been added. If you shop carefully, you may be able to find a 5 gallon pail locally for around $20-25, which will last you for several changes. You can also use ISO68 gear oil, like Mobil DTE26.
https://www.mobil.com/english-us/industrial/pds/glxxmobil-dte-20-series
For the apron, I use Mobil Vactra #2, a ISO68 oil with tackifiers added, which cling to the gears better when not in use, and help to move the oil to the gears and shafts above the oil level in the apron. It is also perfect for the ways and other sliding surfaces on the lathe.
Please do not forget to regularly grease or oil the feed gear and the half nuts behind the apron. That needs to be done regularly and often, or they will wear out. My Kent 13x40 came with a spare feed gear and half nuts, wonder why? They are out of sight and often out of mind, don't forget to lube them.
I've seen some of your other posts before, and I'm guessing that you are the resident oil expert here, so I'm hoping I'm understandable!
HAHAHA! :) I am just another wannabe, well read, and know how to spell, but not necessarily smart about anything. Trust, but verify...
 
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