I should also mention that I don't think olive or vegetable oil would be good, because it would eventually become rancid.

Is mineral oil a good choice?

Perhaps just use the bucket of sand without the oil. Then you simply use a rag to wipe down the metal parts of the tools with whatever oil you find acceptable so there is no problem of it going rancid, or attracting ants.

The key to keeping tools from rusting is not to store them wet or with dirt on them. Use a rag or a wire brush to clean after each use. If rust begins, use a file or sharpening stone on edges, and steel wool or sandpaper on the metal body of the tool. Every year or two, sand the wood parts and use boiled linseed oil to keep the wood from becoming too dry.

This was the method I was taught 25 years ago while maintaining tools in the Forest Service and it has worked well for me ever since. Buckets of sandy, stinky oil of any type aren't necessary.

Thanks to all who replied - every suggestion was helpful, and I'm ashamed to say that I didn't realize mineral oil was a petroleum by-product!

Used motor oil is a more environmental option, as it has to be disposed of somehow. I use it to oil the wood parts of tools, as those will degrade away much faster than the metal parts. When I replace a handle, I give it a good soaking in used oil and it becomes nearly impervious to weather. Which is necessary as I have a tendency to leave my garden tools in the garden.

I have to disagree PNBrown - the only environmental place for used motor oil is in a collection and recycling center, especially in Los Angeles where oil residue is already a huge problem in the ocean.

I disagree equally. It's possible you are not familiar with wood properties. Raw wood soaks up used motor oil and renders it effectively inert. Petroleum is not impervious to biological action either, I don't believe. I'm not a chemist, but I imagine as the wood handle eventually gets cast off to rot somewhere the small amount of motor oil in it is metabolized in the process.

On the other hand, used motor oil brought to collection centers is eventually burnt for fuel. Which is a better end result? Not so easy to say, perhaps.

Used motor oil, having been super-heated in the internal combustion engine, is many times more carcinogenic than unused oil. Both are toxic and considered poisons. I would not soak tool handles in used motor oil simply because I wouldn't want my bare hands to come into contact with the carcinogen on a regular basis. The simple absorption of it by wood is not a chemical process, but is instead a physical one. The carcinogens are not transformed or abated by their contact with non-living wood. Furthermore, using motor oil on the metal parts of garden tools is poor organic practice, as the carcinogenic oil is effectively added to your garden soil. Linseed is perfect for the handles and camelia oil is a fine choice for the metal parts of garden tools. Used motor oil is a hazardous byproduct of modern life that we'll have to be comfortable disposing of in a hypocritical fashion until we progress beyond the internal combustion engine. There are really no proper home-scale uses of it; adding it straight into to the Earth, or putting yourself into frequent contact with it do not make sense.

I don't see what is so great about flaxseed oil, it comes from flax seed which takes energy to grow and more energy to process the oil, even more energy to get it to the place we buy it and more to get it home. Oh BTW, who knows what sort of conditions the flax is grown under or how much native land was destroyed to plant it.

Take care of your tools like your life depends on them, after all, some part of the Earth was destroyed to make that steel. Clean them up with water to remove the soil and air dry as soon as you are done using them, I know, it can be a pain in the butt.

I've always heard and used Coconut oil for maintaining the steel parts of my tools. Put a bit of lemon oil perhaps on the wood parts.

I haven't done any kind of giant studies on the best oil for maintaining tools so I can only offer what I have done with results that seem goo to me. Then again my father never did anything for the tools other than clean and put them in the shed. They lasted for decades.

In reference to the use of mineral oil to keep our tools from rusting. I looked up some uses for mineral oil. We use it on baby butts and delivery of babies. I hardly think it will harm our garden soil. http://en.wikipedia.org/wiki/Mineral_oil

What do bee keepers use for there wooden hives?You guessed it, Boiled linseed oil!!!! The best way I have found is to apply it to all my wooden handles on tools and wheelbarrow handles is to do it in the HEAT of summer so it soaks into the wood.50-50 with mineral spirits.Do it every day for 2 to 3 days and leave them in the sun and the next time you forget and leave them out in the rain it won't hurt so bad.Plus they will last a lot longer by mantaining them this way!

Buying high quality tools and not leaving them outside means they will need minimal maintenance and last a long time. That's really the most conservative and green approach. Many of my tools and wheel barrow are well over 20 years old and doing great. No doubt it helps a lot that I usually make it a habit of putting things away in the garage.

I have used mineral oil (baby oil) to lubricate tools. Yes it's a petroleum product but a small bottle lasts forever when all you need is a few drops. I've also tried Canola oil aka rapeseed, which seems to work okay, because rapeseed oil has been traditionally used to lubricate machinery. WD40, A-1 oil, used motor oil, etc also may work but they are way too stinky and gross and I don't like to stuff like that on my hands.

I have a shovel that my Father gave me.
No oil or paint, has a little rust,but the only wear is from use in sandy-loam the last 60 or so years.
It is not green/ organic, it's just not needed if you clean & hang up your tools.
But if I was going to use oil it would be Boiled linseed oil.
We humans have used it on tool handle & fine benches, chairs for well over 100 years.

The amount of whatever that one might use on a tool handle is so insignificant in comparison to the direct and indirect uses of products and energy one incurs every day that worrying about it amounts to a distraction from much more critical variables.

I much agree with Mike that being careful with tools to save the metal is important. I am an offender in that regard. However, I have re-handled many tools, using scrap wood. Every junk shop is overflowing with servicable but un-handled hand tools. You know what to do.

Very helpful thread. Not having had any family member of friend that gardened to pass down this kind of information, I'm always reading information, and using trial and error but SO much better to hear from someone who has had experience. I've also read articles about the bucket of sand with the oil and had the same concerns about using motor oil.

I found the suggestions dicot made and others who posted similar advice, settled that question for me. . I really appreciate when people who have experience share that on the forums. Thanks a lot.

Boiled linseed oil is what I have seen recommended instead of motor oil.

Thank you! :-)