Oils

Hi all, was at our club over the weekend and someone said you should not use car oil for general lubrication, but get specific Lubricating oil. Has anyone else heard that ?

What are you lubricating?

Multigrade detergent oils intended for cars are not good for machine tool spindles or ways, or the cylinders of steam models, for example. ISO 32 hydraulic jack oil is great for spindles, way oil is great for machine ways, and thick steam cylinder oil is best for steam cylinders.

Automotive oils contain additives designed to clear deposits in the engine,and also have specific viscosity characteristics with temperature.

For small, lightly used, lathes it probably doesn't matter much, but I prefer to stick with the manufacturers recommendations. Basically straight hydraulic oils for spindle and headstocks, thicker straight oils for feed gearboxes and specific slideway oils for slideways.

Andrew

I have been lubricating the Smart & Brown with 5W30 fully synthetic for years, all the lubrication is oil and total loss, there has been no noticable wear since doing so. Modern oils are light years ahead of the stuff available in the 40's.

Jeff and Andrew are correct.

Automotive oil only wins because you may have half a container of it on the shelf and that it is easier to find a local supplier. It is certainly more expensive. Your local lubricating oil supplier is unlikely to turn away your business.

My lathe uses more oil than my old British bikes.

JA

Very much more expensive if you use synthetic oils.

Edited By JA on 15/08/2022 16:45:30

If the machine being lubricated does not need or can not benefit from modern sythetics it's just a waste of money. Straight mineral oils are ALL oil, multigrades have alsorts of additives that are Not oil ! Noel.

Sorry all, I should have been more specific, the conversation was about model steam locos, but could apply to lathe beds etc. I generally use Halfords Classic car 20/50 which I don't think has many if any additives? and its reasonably thick ??

Old mart, well said mate. I changed the headstock oil on my old DSG using hydraulic oil as specified only because I had a can of it , but modern engine oil like 5/30 syn but be fine and in the gearbox too !.If a bloody great Volvo road grader towing a 6 ton roller with about 10 gallon of 5 /30 syn oil in its gearbox manages , it will certainly be ok in a lathe headstock or gearbox.

How about putting hydraulic oil in the Volvo?

Andrew

Leaving aside the OP question on steam engine oil, 5W-30 engine oil is significantly different to the ISO 32 hydraulic oil often specified for lathe spindles and some lathe gear boxes. Nuto H32 has a 40 deg C viscosity of 32 cs and a 100 deg of 5.4 sounds pretty close to 5-30 right? Wrong, a typical 5W40 oil (Castrol GTX) is nearly twice as viscous. It is 9.7 at 100 deg and 55 at 40 deg.

Just becuase someone has used it with no apparent ill effects does not mean it is OK. Our applications my be non critical but it is generally best to stick with the recommended lubricants. One particular point is the additives in some oils can have adverse effects on copper and copper alloys e.g. bronze bearings.

https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/D1CFEDB7F95B365F8025827B0053876F/$File/BPXE-AYJQ74.pdf

https://cdn.lubefinder.net/media/attachments/m/o/mobil_nuto_h_series_tds.pdf

Robert G8RPI.

Edited By Robert Atkinson 2 on 15/08/2022 18:45:08

Whether the grade of oil matters or not varies with the application. Hobby lathes are lightly loaded so the oil is non-critical and any oil is better than no oil. Although ISO32 is a good all purpose workshop oil I tend to splash 20/50 on my kit because it's cheap, handy, reasonably thick, and low on additives. I sometimes treat slides to some way oil, but there's not much advantage unless the machines are being pushed hard. As Way Oil is thick and sticky it resists being squeegeed out by the slides, which is useful on busy machines.

Additives can be an issue. One definitely to avoid are EP gear oils, EP is short for extreme pressure, achieved with an additive that attacks copper alloys, which is bad news for any machine with brass or bronze bearings - quite common in tools!

Other additives are more likely to waste money than do harm. They're added for various purposes, often associated with hot engines or other automotive needs. They discourage emulsions, foaming, or improve heat performance, including improved cold-start and anti-waxing.

It is important to use the right oil whenever a machine is stressed or has a critical function. Aero-engines have a high power to weight ratio and are required to keep people safe in the air for several hours. Also important to use the right oil on light mechanisms like clocks and sewing machines. WD40 and 3in1 are both excellent clock killers - the first removes oil with a burst of temporary lubrication whilst the second gums up and forms a grinding paste by collecting gunge. Lathes aren't delicate, run at lowish RPM in short bursts and don't drop the operator in mid-ocean.

Dave

Edited By SillyOldDuffer on 15/08/2022 21:18:24

As Robert says oils with certain additives have a detrimental effect on bronzes, we run a new Leak compound in the museum boat and we're instructed in no uncertain terms by the maker to only use straight oils because of this very problem.

As above... No-one has yet mentioned that detergent additives in motor oil are there to keep contaminants (including soot, etc., blown past the piston rings) in suspension so that the full-flow oil filter will then sequestrate them. Motor oil is full of other, expensive additives designed to preserve the oil and its designed performance characteristics in the horribly demanding environment of an ic engine.

Machine tools are different. They need oils which encourage contaminants to settle out and lie harmlessly in the bottom of the headstock, gearbox, etc. Anti-foaming and anti-corrosion additives are present in the hydraulic oils mostly specified for machine tool use. They are also very slippery. There is no point using anything else - which is also likely to be more expensive. On the other hand, it probably won't hurt, except...

I read somewhere that motor oils, because of the hydrophilic detergent content, absorb water, so may paradoxically increase the risk of rusting. In an ic engine, the oil gets hot enough for absorbed water to evaporate away. Engines standing idle for a long time can rust internally significantly, notwithstanding the oil inside. I once had to store an old cast iron surface plate in a very damp garage. I covered it with paper, and soaked the top with synthetic engine oil. It rusted spectacularly. Older and wiser now...

SOD. I also used to warn people to avoid 3-in-1 oil, but I have been challenged by others on this forum recently. The old formulation we all hate was vegetable oil-based. Now it's apparently mineral oil, and doesn't oxidise to a gummy mess. (I'm expecting a cheque from the manufacturers...). However, I see no need to use it, because I have gallons of light hydraulic oil, which is a great general-purpose 'oil can' oil.

I believe there are EP additives that don't attack yellow metals, but it's difficult to know what you've got in a can, so your warning is appropriate.

Edited By Kiwi Bloke on 15/08/2022 22:25:24

Most/many modern automotive gear oils are safe to use with copper and yellow metals. Read the packaging to make sure. Most changed the nature of the sulfur additive a few years back to make it compatible. If it says on the label its safe for bronze, copper, yellow metals etc. all is well. But I would not use it on lathe gears, largely because of the stink, and because they are nowhere near EP or Extreme Pressure like a diff or gearbox transmitting 100HP etc.

ISTR that 20/50 oil is about the same viscosity as ISO32 hydrualic oil and 90W gear oil, rather surprisingly.

Indeed. for aircraft pistion engines that are not going to be run there is generally a requirement to replace the normal oil with a special inhibiting oil. This note from Shell confirms that detergent "W" oils are an issue in this respect.

https://www.shell.com/business-customers/aviation/aeroshell/knowledge-centre/technical-talk/techart09-30071425.html

Rust chemistry isthe same in machine tools

I use Chainsaw oil as it doesn't get flung off. I use that on all my motion including eccentrics, and I use compounded 680 steam oil in my mechanical lubricator.

I think engine oil will be just fine for general oiling round.

As an aside, one reason oils and hydraulic fluids absorb water is because its better its held within the oil, even if its in an emulsion, than for droplets of water to remain on ferrous surfaces. This is especially true of brake fluid.

Edited By Jon Lawes on 16/08/2022 10:31:39

In the interests of avoiding possible confusion, note that the discussion has been about hydraulic oil, not hydraulic fluid, i.e. brake fluid.

Swapping from straight to detergent oil is a common killer of old aircraft engines and is far more expensive than the couple of hundred quids worth of oil.

Like many here, I lubricate my lightly used and loaded benchtop lathe with oil that I already had - Dextron3 ATF, which is basically hydraulic oil with, unnecessary for the lathe, dye and detergents.

When I have to buy oil, it will be the 'correct' stuff, but going by current use that's several years away.

The change gears get a squirt of white lithium grease for the same reason.

There are quite a few types of ATF around. Some modern ones are designed for 'lubricated for life' 'boxes, which are effectively hermetically sealed, because the fluids are hygroscopic. Also, the 'slipperyness' of ATF has to be carefully controlled, because of the numerous wet clutches in auto-boxes, which also, as far as I know, don't have plain bearings in them. I don't think these modern ATFs would be ideal for our machine tools, but I don't know about earlier types. Comments about detergents stand.