automotive lubricants (ATF, manual trans fluid, or heavy motor oil) as bike chain lube?

Question

Good afternoon,

I'm quite mechanically inclined (formerly an auto mechanic and currently an engineer) but relatively new to cycling. Compared to other contexts I'm familiar with, I've noticed that bike chain lubricants, for example the Park Tool chain lube (https://www.amazon.com/Park-Tool-Synthetic-Blend-Bottle/dp/B000AOA290) or the Finish Line wet chain lube (https://www.amazon.com/Finish-Line-Bicycle-Chain-Lube/dp/B000WYCD5O?th=1) are very expensive per quantity compared to automotive lubricants. I'm wondering if anybody has extensively tried any of the following as bike chain lubricant:

-Automotive Transmission Fluid (ATF)

-Manual Transmission Fluid / Transfer Case Fluid / Gear Oil

-relatively "heavy" motor oil, ex. 10W-40

In my general experience I've found that ATF is usually the best lubricant for almost any purpose, for example I've found that ATF lubricates air tools better than air tool specific lubricants.

I'm planning on trying ATF out before I spring for another bottle of Park or Finish Line chain lube. Has anybody else tried any of the above for bike chain lubrication?

Answer 1

In my experience, the objective of a good chain lub for a bike is to maximize lubrication time while minimizing dirt attraction.

That happens for three reasons:

• The chain is totally exposed in a performance bike. You have dirt coming from the ground, the wheels, the air...
• You legs are surprisingly close to the chain, and may rub it quite easily.
• The situation where your chain snaps from the crankset and you may have to reinsert it manually in the crank teeth is not quite rare.

That is why there are a great variety of chain lubs. You can go from minimum dirt attraction (wax) to the maximum (wet).

I would say that if you are perfectly happy with a wet lub, a switch to an ATF one would not pose a big problem. What you do not want to you use are solvents, most notably WD-40, they do not act as a lube long enough.

Do not use thicker oils, as standard engine oil: they will render your chain a mess in not so long and they won't penetrate deep enough in the links.

On the other hand, if you want to minimize dirt attraction, something I prefer personally, I would use a bike chain specific dry lube or wax.

As a bottom line, you know that a 120mL bottle lasts like forever? You have to apply only one drop per link, meaning only 0.05mL per link.

Answer 2

You can use almost anything you like as chain lube on a bike as anything is better than a dry squeaky chain. However for chain longevity, lasting lubrication and lack of oil flinging.. Specific stuff is in most cases better. When I used to motorcycle and motoX I ended up using a chain lube called PJ1 Blue Label, it was awesome stuff especially as when used on my immaculate road bikes the lube wouldn't fly off and coat my rear wheel in grease. It goes on from the straw like bubbling thin oil and is quite tacky, then it thickens up. I always wiped off the excess whilst it was still thin. It was soo good I transferred its use over to my pedal bikes too and it worked like a charm.

Answer 3

Motor oils intended for use inside an engine make for terrible chain lubricant.

All engine oils are designed to trap and encapsulate combustion byproducts. That's the opposite to what a chain needs. So the road dust ends up turning the oil to a grinding paste that eats your cogs and chain over time.

Additionally, used motor oil is a carcinogen and should be avoided. https://pubmed.ncbi.nlm.nih.gov/2612787/

So motor oils rank down there with water, piss, chocolate or banana as a chain lubricant.... marginally better than nothing but not by much.

Answer 4

This may not be a popular answer, but I recommend 80-90 weight gear oil. It takes more time, but you will get 10x the number of rides as the "proper" chain lube.
To lube the chain with gear oil:

1. Remove the chain from the bike
2. Thoroughly clean the chain with a de-greaser, wash with water and immediately dry with compressed air. Be sure to blast air in each roller to push the water and left over de-greaser out.
3. In a left over card board box, stack the chain on itself with about 10 links per row. This should make a rectangular shaped chain stack, similar to how a new chain arrives in the box. Lean this stack on the side of the box. The box side will hold the chain shape during the rest of the process.
4. Drip gear oil on the top of the stack. It should start traveling to the bottom of the stack like a "plinko" game. You may have to do several coats before it gets to the bottom of the stack. The box will soak up excess oil.
5. Leave it overnight.
6. Wipe the chain with a clean towel until no more lube comes off.
7. Put it back on the bike and ride.

Because you have thoroughly wiped the chain, the gear oil that is left is inside the rollers, where you want it.
In addition, it will not attract dirt because it is trapped inside the roller.
Because gear oil is thick, and gets thicker the longer it's outside, it will not fling off easily.
It will last far more rides and washes than normal bike chain lube. The other benefit is that you do this off the bike, so the excess lube does not get on your chainring(s) or cassette cogs.

The biggest downside is the time it takes to do this. Personally, I don't mind the extra time if it means I don't have to worry about lubing the chain all the time.

Answer 5

Automotive lubricants aren't ideal for a chain. Here's why.

Chain lubricant should be:

1. Very, very thin when you apply it
2. Extremely thick when you park the bike for waiting its first ride after new chain lubricant
3. Reasonably thin when you start riding the bike
4. Extremely thick when you again park the bike

Automotive lubricants don't satisfy these criteria. Automotive lubricants are specified something like 5W-30 or 0W-20. For example 5W-30 means it has a thickness of SAE 5 when cold, and SAE 30 when hot. Each SAE thickness of course varies with temperature, so SAE 5 oil when cold is thicker than SAE 30 oil when hot (but SAE 5 oil when cold is thinner than SAE 30 oil when cold).

So automotive lubricants are only designed to have a certain viscosity profile as a function of temperature. Generally you want as little viscosity change as possible when temperature changes.

Bike (and motorcycle) chain lubricants, on the other hand, need a different viscosity profile. They need the viscosity to be thin when agitated, and gradually become thick when left undisturbed. This feature is called thixotropy.

Thixotropy (shear thinning property) means that if you take a motorcycle chain lubricant, put it into a container, agitate it hard for a long amount of time, it becomes thin. You can observe this by tilting the container and seeing how quickly the lubricant responds.

Now, if after agitation you leave the chain lubricant settle for a day, and try to again tilt the container slightly to see how quickly the lubricant responds. You will see a difference -- the agitated lubricant is thin (low viscosity), but the settled lubricant is thick (high viscosity).

Also, to make the lubricant extremely thin, far thinner than when riding the bike, when applied, two additional helpers may be used:

1. The lubricant may be stored in a spray can, so the act of spraying it agitates it very thoroughly, ensuring it's extremely thin after coming out of the nozzle
2. The lubricant may also contain low-viscosity volatile solvents in it, to make it even more thin, and then those solvents evaporate very quickly and leave behind a thick base oil

So what you want is a motorcycle chain lubricant in a spray can.

Bicycles have an additional property that they are very low tech. So practically any oil that doesn't oxidize works in a chain. So motor oil, it works. Gear oil, it works. WD-40, it works (although it contains maybe too little oil and too much solvents). Gun oil, it works. Basically any oil apart from something like food oils like rapeseed oil works. The food oils work too but they oxidize so only for a while.

Actually, bike chains can be lubricated by water too! If you have ridden a bike long distance in the rain, you notice it doesn't squeak. The squeak starts after the rain stops. This demonstrates that as long as new water is fed into the chain, the water lubricates the chain. The only problem is that water is not a long-lasting lubricant, it doesn't stay in the chain for long.

Actually, some cyclists prefer to lubricate their chain by Teflon flakes in a volatile solvent (called "dry lube"), or even wax the chain. Both of these are inferior lubricants and would for example never work in a motorcycle. But bike, being such a low-tech device, works for a short amount of time with these inferior lubricants that don't flow and thus aren't replenished.

So automotive lubricant, it works, but isn't ideal. You will find it's hard to get inside the chain when cold, so you may prefer to heat up your chain in a hotplate before applying motor oil on it. Also motor oil doesn't become thicker when left unagitated, so it will not stay in the chain for as long as a true thixotropic motorcycle chain lubricant in a spray can would stay.

An advice: leave all bike lubricants on the bike shop shelf, don't buy any of these. If you buy a bike lubricant, it's 99% certain you will buy crap (because bike is such a low-tech device that even crap works). It's also 99% certain that the crap you buy will cost ten times the amount of same volume of printer ink.

Buy only motorcycle chain lubricants in a spray can. They aren't terribly expensive, and they are extremely well engineered to work on a high-tech device that is the motorcycle. So they will work even better on a low-tech bike.

Before lubricating the chain, wait until the rollers are shiny clean (if they aren't it doesn't need new lubricant) and wait until you hear a very slight increase in chain noise (if you don't hear it, it doesn't need new lubricant), take the worst dirt out of it using a pair of stiff brushes, take even more dirt out of it by using a microfiber cloth, and only then lubricate it.

After lubricating the chain, take the excess lubricant away from it by using another microfiber cloth.