Uses in the shop for Gear Oil?

[mksj]

I think that was a smart decision to sell it. You may want to try the Amsoil marine gear drive oil, the diffidence in my gear head mill was significant over the stock oil, they just do not recommend synthetics during the break in on machines. Interesting in compressors that with stock mineral oil it is suppose to be changed every 200 hours, switching to synthetics it is around 2000 hours, so greatly increases the time interval. It is still good to change oils annually. Alternative would be something like Mobile heavy medium (ISO 68) gear oil, which is also what is specified for the lathe carriages and gearboxes. Most lathe recommend ISO 32 for the headstock, and that is one area where your comment about splash lubrication and flowing down to the bearings is important. In very hot environments some people use an ISO 46, but I always used ISO 32 in my PM-1340GT headstock and my current ERL-1340.

 

[Jake P]

I’m a little confused Mark, so please forgive me if I’m missing the obvious.

A few posts ago you mentioned the following:

This is also similar to what is recommend with the RF clones and the PM/QMT gear heads "Gearbox ISO 68, such as SAE 80W90 auto gear oil, or (recommended) Mobil DTE Heavy-Medium circulating oil (about 3 qts".

And according to the PM 1340GT manual they also recommend the ISO 68 oil. The following is from the 1340GT manual:

“Recommended lubricants
Gearboxes: Mobil DTE, or equivalent, Heavy/Medium circulating oil.”

According to what I can tell the DTE Heavy/Medium is an ISO 68. And the DTE 24 (that I have now in my RF-45) is an ISO 32.

So both the 1340GT and the RF-45 manuals recommend an ISO 68 oil.

But then in your last post you said this:

…..but I always used ISO 32 in my PM-1340GT headstock and my current ERL-1340.

So I’m wondering why you use the lighter oil? Is the manufacturers recommended oil not appropriate? Or am I not understanding the differences in the oils?

It would seem that the previous owner of my RF-45 also felt that an ISO 32 oil was appropriate rather than an ISO 68 oil.

So I’m trying to figure out why.

As to the Amsoil recommendation, it seems to me that since it’s advisable to change out the oil annually regardless (and that’s another thing I just don’t understand) the cost difference is not justifiable to my usage if I’m changing oil annually and (in my case) not ever hitting max hours.

 

[mksj]

ISO 68 is used in the gearbox and carriage of most lathes, if your lathe has a pump oiler in the carriage that feeds the ways then they recommend way oil which is typically Mobil Vactra #2 or Mobil Vacuoline 1409 (both are ISO 68). When it comes to the headstock, the original 1340GT manuals specified an ISO 32 gear (or hydraulic oil) and this is the generally the recommend oil for splash lubrication headstocks. Just about every lathe manual specifies this. A few lathe distributors use one oil for everything to minimize stocking, so they specify ISO 68. QMT/PM is the only distributor that I have seen that specifies ISO 68 for all their lathes headstock, all the other manuals I have seen use ISO 32 in the headstock. This includes the original manual and also the Eisen equivalents. Any oil is better than no oil, if you live in colder winter climates I would use an ISO 32. You can discuss this with QMT/PM. but the other splash lubricated lathe manuals specify ISO 32 (you can check the Grizzly lathes, Eisen, Sunmaster, etc.), I actually have not seen one that uses ISO 68 in the headstock. The difference in viscosity is not that significant that it matters, I have always used ISO 32.

Gear head mill is typically ISO 68, SAE 20 motor oil (non detergent), SAE 80 gear oil. The difference with synthetics is that they have a lot less foaming and cavitation, if you are doing a lot of high speed milling, a synthetic should run cooler and with less heat build up. This was the case with my mill, I typically ran in the 2000-2400 RPM for aluminum, the head was significantly cooler, the air bubbles cleared much quicker from the oil and my top speed increased (so more power to the cutter). That is why I recommend a synthetic oil in this situation.

 

[Jake P]

OK Mark, I understand now.

Thanks for the clarification. Your efforts are much appreciated!

 

[Jake P]

Follow up question for the oil gurus:

Is an AW hydraulic oil comparable/compatible to an ISO oil?

 

[mksj]

Yes. AW-32 would be ISO-32, AW-68 would be ISO68. A manual lathe is light duty for this type of oil, that the difference in brands probably means very little as long as you change the oil on a regular bases (like every 1-2 years or per the manual). In a gear head mill, you may see a bit better performance differences with a high quality oil or a synthetic base given the discussion points mentioned about not using ones with extreme pressure additives. Hydraulic oils must withstand high pressures through hydraulic pumps, have anti-wear/foam agents and have anti-rust additives.

 

[Jake P]

Yes. AW-32 would be ISO-32, AW-68 would be ISO68.

Thanks again Mark! I just wanted to make sure there were not some additives to the AW that would be harmful to these machines.

The photo is from a store local to me (North 40) that is something like the chain “Tractor Supply”. So it would be cheaper going this route than online with shipping.

 

[sdelivery]

The customer I have been at for a couple days uses gear oil instead of way oil...in ALL his machines (cnc & manual) and has for at least the last ten years I have been servicing his equipment.
I have seen zero problems with yellow metal damage.

 

[Jake P]

The customer I have been at for a couple days uses gear oil instead of way oil...in ALL his machines (cnc & manual) and has for at least the last ten years I have been servicing his equipment.
I have seen zero problems with yellow metal damage.

As I understand it, there are gear oils that are safe and gear oils that are not.

 

[mksj]

The issue is with EP (Extreme Pressure) additives that are more commonly found in some motor/gear oils, these can damage yellow metals, clutch packs, synchros, or surfaces that are softer. Standard gear oil and hydraulic oils are very similar, although the additives can vary somewhat, but either can be used in these applications (so like the Mobile DTE hydraulic oil series and the their named gear oil series). Way oil is a bit of a different animal, so it is not something I would use in the headstock or gear head mill, it is more designed with higher concentrations of tackifiers and I am not aware that it has anit-foaming agents. It is sometimes used in the carriage which has low speed gears and the oil is picked up on the gears from the sump. Also some carriages have oilers to the ways, etc. The only way oil that I am familiar with which is also recommended to be used for gears is the Mobil Vacuoline series.

Products

Mobil Vacuoline™ 1400 Series oils are extra high performance lubricants specifically designed to satisfy the requirements of machine tools that use one oil for both hydraulic systems and way lubrication

www.mobil.com