No Gear Oil Reading in my Headstock

The more pics of the PM-1660TL I see, the more I think that the G0509G must be a very close cousin. The head stock gears look pretty close to the same. I have a slow leak in the headstock but maybe a quarter inch over a couple of years. I keep an eye on it.

I had a sticking lead screw gearbox when I first got mine. Was just a burr on a bronze positioning fork and easy to fix. I took the transmission cover off. Here is a picture. Probably not too different than what is on yours. The gear boxes are very nice. I was impressed with the gear quality in both the headstock and the transmission.

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I went out on the town this morning to find the oil pictured below. It is ISO VG 32. I went to 3 different places, and I could only find ISO AW 32, which I gather is the same thing with some additives in it.

So I ordered what is in the picture below on Amazon, and when I came home I found that I did, in fact, have 2 quarts left over from my oil change. I added 1 quart which brought it up to the proper level.

When I did the oil change 2 or 3 months ago, I used white Teflon tape, and I tightened the drain plug as tightly as a normal person tightens a bolt; I am confident that I did not undertighten or overtighten it. Today, I reinstalled the drain plug (which required removing and replacing all of the oil).

When I did the oil change 2 or 3 months ago, I noticed that the oil looked “aerated” or foamy in there as seen through the sight glass. I neither posted this observation on the forum nor contacted PM about this aerated looking oil.

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Further observations:

(1) I see that PM is now recommending ISO 68 for the headstock. When I looked 4 months ago, the PM website said “Light Hydraulic Oil” which is ISO VG 32. I wonder why they changed this.

(2) Not surprisingly, the oil level in the sight glass drops a little when the machine is in use.

(3) I’m back working on the lathe again, and I no longer notice the aforementioned aeration in the oil.

(4) You know after you do an oil change on your car and you add enough oil to get the dipstick to the proper level? After you drive the car a bit, it is recommended that you recheck the oil level. It is often the case that you need to add a little more oil. I wonder if that is what happened to me here.
 
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It is so easy to overtighten a tapered fitting. If teflon tape is indicated then it is a tapered thread seal. I know you like to really torque things, but this is not holding something mechanical, and it is not a grade 8 fitting. It needs to be just tight enough to not leak, and not tighter. as overtightening distorts the tapered threads and causes leakage. You might want to chase the threads with a tap and clean up the plug with a die, or replace the plug and get it just right. In any case leakage from the drain plug could be checked one way or another to see if it is coming out there.
 
When operating the machine oil is displaced through the system, so naturally the oil in the reservoir will be reduced. Check the oil before starting work, not while running. I would think once per day would be plenty often unless you see oil running across the floor.
 
The Harrison Boxford I had used a manual oiler for headstock gears and they were still fine after 45+ years. leading me to believe that it is difficult to wear out the gears on your lathe if it was low on oil for several hours.
The back gears rely on periodic grease or oil only.
 
Headstock oil is an ISO32 oil, I have several manuals on the SunMaster lathes and they all recommend the same. Maybe someone is confused, but I would follow the manual. The feed/thread gearbox is ISO68 and so is the the carriage. Since the carriage oiler also provides oils to the Ways, I would suggest Vactra #2 Way Oil or better yet Vacuoline 1409 (ISO68) in the carriage. The Mobil oil is an example there are many equivalent oils by other manufactures. I purchased a 5 gallon pale of Vacuoline 1409 through a local oil distributor, it can also be used in gearbox.
In my headstock I use Miles oil which is $54 for 5 gallons shipped from Zoro, also they have a version with rust inhibitors which is new:
www.zoro.com

Miles Lubricants 5 gal. Pail, Anti-Wear Hydraulic Fluid, 32 ISO Viscosity M0010011303 | Zoro

Order Miles Lubricants 5 gal. Pail, Anti-Wear Hydraulic Fluid, 32 ISO Viscosity, M0010011303 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.
www.zoro.com www.zoro.com
https://www.zoro.com/miles-lubrican...scosity-10w-sae-amber-m0010020103/i/G5104167/

Foaming of the oil is common with speed in a splash lubrication system, oils also have anti-foaming additives, the bubbles should dissipate quickly when the machine is stopped. If you did not have any oil level issues before the oil change, then most probably would be leaking from the drain plug. As I mentioned, clean up the oil, drain and reseal the drain plug using some heavy Teflon sealing tape. Run the machine for 30 minutes and then check for leaks. You should check the oil levels as a precaution each day, unless you notice a puddle on the floor. The carriage needs to be topped up periodically because the it is used up feeding the ways, I do 2-3 pumps every 3-4 hours and when done to push out any debris. I always wipe down the machine with way oil when done, most tapping oil will stain the exposed metal parts.
 
The listing is generic and not meant to be used in the headstock of your lathe, it is just how it is listed across their website as headstock/gearbox oil, and for your machine it would be the gearbox. There is almost no lathe headstock that uses an ISO68 unless it is a low speed. At high spindle RPM an ISO 68 will present too much drag, will get more aeration and may not flow to the bearings as well in particular when cold. You can call QMT technical, but I have several manuals on these lathes made by SunMaster including those that are from Grizzly's South Bend lathes and they all specify ISO32. I would not use an ISO68 in a lathe headstock, the highest I have seen is ISO46 used in very warm climates. Maybe QMT needs to read their manuals, check with them.
 
FWIW Mark, PM actually specifies ISO68 in the headstock of their 1440GT. The manual for Erik's machine, from what I can see, doesn't specify a viscosity. I am with you though, I never heard of putting ISO68 in a headstock.
 
The PM-1340GT manual says Mobil DTE, or equivalent, Medium/Heavy circulating oil which is ISO 68.
Screenshot_2021-02-08 PM-1340GT-v7-2020-10-1 pdf.png
 
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