Overview for all Servicing the RB may needs like lubrication
Content from the linked Google+ article:
Which one should I use? Well, this debate has been going on for years, there's enough engineers and technicians out there arguing this to make you sick. I'm a machinist and have been for about 10 years now, some of the machines we have at work are from WWII era of time and one from even before, the only thing we use on slide-ways is oil and every one of those machines runs perfect and repeats. The main machine I run is a 1957 Bullard 57" Vertical Turret Lathe, and trust me when I tell you, it gets used. Only oil is used on the whole machine, not one spot has grease and it runs like new. I got a maintenance tech that's 76 years old and trying to retire, he will slap the shit out of someone if he sees them use grease on a way. A "way" is any surface that is used as a travel, so your rods for the 3 axises are considered ways.
Vegetable oil should NEVER be used to lubricate mechanical parts because it always leaves a solid deposit which later will stuck the parts you wanted to lubricate. Vegetable oil will gum up, attract dirt and dust, and eventually end up a huge mess. DO NOT use it.
Mineral oil is a food-safe oil not normally used as a cooking lubricant, but it is the go-to for replenishing woods and lubricating mechanical parts of cooking utensils. It won't gum up, and is OK to use in a pinch.
Sewing machine oil has the consistency of water. It is also completely clear and odorless. Oil also has a shelf life. If it has turned yellow, it is old and should not be used. If it has an odor, it is not the correct oil to use. I've been doing this long enough to know that some will have a preference for some type or another of specialty oil. Use at your own risk. I am going to stick with plain old sewing machine oil. Most machine oils are a bit thin; they'll get into crevices like in door hinges, but they're lighter-weight and more volatile, and will eventually evaporate or work their way back out this is why you need to re-apply on a consistent basis.
Please note that the purpose of any lubrication is to form a thin protective barrier between (usually) metal parts. The key word here is 'thin'. A little goes a long way. The parts that make up a sewing machine usually fit together with very close tolerances. The oil's job is twofold: One is to form that barrier to prevent premature wear and tear, and the other is to keep the machine running quiet.
Silicone sprays are great for metal-on-metal, but they are incompatible with some plastics, and attract dust and particles that can stay deposited and scar the machine ways.
Gears, on the other hand, require grease. The churning of grease in gears and bearings results in high energy-consumption losses and heat generation. Energy consumed by oil in a similar application may be only a fraction of that of grease.
WD-40 IS NOT A LUBRICANT. It is a penetrant / water displacer using Alephetic Hydrocarbons (AH's) as part of the compounding to accomplish the task. Certain AHc's are extremely corrosive, even though they are technically petroleum, the refusal of WD40 to release the chemical contents that led to its banning. Being a penetrant by virtue of the descriptive, it has an acidic/capillary component to it to break down oxidation. It is not allowed to used at all in the NBS labs because of it's corrosive action on certain metals. It may be good to free up rusted parts, but you never want to use it to try to lubricate clean ones. (Thanks +William Eades)
The pictures posted represent a bottle of sewing machine oil my wife got for me (@ K-mart) when she was out, she had overheard the conversation I was having with a friend about the size and applicator on a traditional sewing machine 3-in-1 oil and thought this was great, and I do also.
So in conclusion go get some sewing machine oil, and apply it at least once a week to all 6 of your rods and to your z screws also (the screws are probably the one place you can get away with using regular bearing grease). The more you use the machine the more you should lube and if you let it sit for too long you should also lube it before use. Besides, no matter in what country or corner of the earth you are, sewing machine oil is readily available everywhere to be purchased, comes in a convenient size bottle that is easy to use to apply.