Project Garage Part XII: Liquid Magic

by Sarah Forst

Who among us has not identified a fluid on the driveway or garage floor by color, smell, or even taste? (Don't drink the Kool-ant...) At any rate, you know you're a true gearhead when the intoxicating scent of a fluid can conjure up memories of changing the clutch, bleeding brakes, or installing bushings. The only way to identify a true gearhead is by the stock ingredients in his or her garage pantry; and maybe how well he or she can recognize them out of their containers.

But first, don't cry over spilled milky white liquid (likely an oil/water mix). You don't want to leave any stains or spills on your garage, especially if you've covered the floor with some dazzling garage paint. And in some cases, knowing what you spilled can dictate how to clean it up or at least what needs to be refilled.


fluid puddlesSome examples of fluids and their puddles on cardboard stock.
Gas: evaporates very quickly so you're likely to only smell a leak rather than see one. 

Brown or golden puddle: newer oil; dark brown or black puddles are older oil.  Engine oil on the driveway often produces a beautiful rainbow puddle that looks like a melted bag of Skittles.

Clear: usually just condensation from the air conditioning.

Red (light to dark): automatic tranny fluid; usually fairly thick, and slippery. 

Golden to light brown:  brake fluid, typically medium thickness and slightly oily and found near the tires.

Light brown: power steering fluid, usually medium thickness. Sometimes ATF is used for power steering fluid so it may be reddish. 

Green or blue: coolant- slightly viscous and sweet smelling. Though it's sometimes bright pink or orange or even clear if you're using distilled water in your radiator. Hopefully an increasing temp gauge isn't your first indication of a leak! 

Thin (like water) and usually any bright color: windshield washer fluid, often blue but sometimes orange or green, with little to no smell. 

We discussed how important good prep was for getting a concrete slab ready for floor paint in Part III of this series but perhaps you prefer your floor "au naturel." If so, there's at least a few ways to keep it clean. A concrete degreaser can be used to clean a small oil stain. Treating a larger stain with kitty litter or a poultice powder or cleaner (found at home improvement stores) will help to pull some of the oil out of porous surfaces like concrete. A good scrubbing with a degreaser before spreading the kitty litter can before it dries. Use a stiff broom to grind the poultice in well and let it sit a few hours. Sweep it up the next day and the oil should be gone.

Rust stains can be remedied with lemons or white vinegar, a few minutes of sitting, and a water rinse.  A high concentration of TSP or even laundry detergent mixed with boiling water (1:3 TSP to water) can also be effective. Let it sit on the stain for 15 minutes before scrubbing.

One of the toughest stains to remove comes from leaking or damaged batteries, which usually leaves a rust colored or green stain. If you're going to store batteries, put a box top or something under them to somewhat protect the floor. Battery acid can eat through concrete leaving the floor pockmarked; the earlier you clean the stain, the better. As soon as you notice the stain, use tri-sodium phospate or any alkaline based (baking soda or concrete degreaser) solution to neutralize the stain. Plain water will only spread the stain and push the acid deeper into the concrete. Apply oxalic acid (like Bar Keepers Friend) or a battery acid cleaner to remove the remaining acid burn stains. It's typically a powder that you mix with water to a paste and then spread on the stain. A pressure washer and some stiff bristle brushes combined with lots of elbow grease can do the rest. Bubbly or crusty white stains indicate concentrated sulfuric battery acid and cannot be expunged. 

With floor paint, you have to be a little less rough. Something like Simple Green usually does the trick or Griot's Garage sells an Oil and Grease Cleanser that has no harmful VOC's, a neutral pH, and has no petroleum based ingredients. It also can be used to degrease the engine bay or even for use on your garage clothes though battery acid will eat through anything (instant acid wash for that 80's looking denim).


DirtyIt's been months (probably a year) since the last detailed floor scrubbing and it shows. There are stains from all kinds of spilled or leaking fluids.
Clean30 seconds of Simple Green and elbow grease and the floor looks pretty good.  Imagine if I hadn't just cleaned a 2' diameter circle!
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Tuesday, August 26, 2014 9:34 AM
You have to try krud kutter from Home Depot, cleans much better than simple green, especially with oil spills.
Tuesday, August 26, 2014 3:20 PM
Great stuff! Small side note: Brake fluid is hygroscopic, not hydroscopic, even though it doesn't sound right. MIQ legal issues aside (whatever they are), for street vehicles, brake fluid should be completely flushed at no more than 24 months in typical climates. In high humidity climes, 12-18 months would be better. For racing or track-focused cars, it may need to be flushed before and after every track day for the common racing fluids.
Tuesday, August 26, 2014 8:17 PM
For R134a Refrigerant you need to throw that blue can AWAY!

Don't use any of these fancy cans with Stop leak, oil additives.... you will do nothing but screw up an AC System. The only additive you should ever add is a UV dye so you can find a leak (Or a metered amount of oil if you replace an A/C component.)

Modern A/C condensers have small passages that the stop leak additive will clog up. Second if you have an expansion valve system (which most imports do) you will gum up or jam the valve.

I learned my lesson on stop leak on my 94 Civic.

Sorry for the rant. Carry on.
Thursday, August 28, 2014 8:15 AM
The pressure gauge is also the wrong way to do it, those are marketed as a cheap band-aid alternative to a proper service and they can damage the a/c system by over or under-filling. The refrigerant is specified by weight. The only correct way to do the refrigerant is to evacuate the system (legally!), repair the leak, pull a hard vacuum to remove all moisture and air from being exposed to open atmosphere, and then add a specified weight of refrigerant, and sometimes lubricating oil. Topping off with one of those cans make work in the short run, but you are running the risk of damaging components. Other than UV dye, there are no good additives either.
Sarah Forst
Sarah Forstlink
Thursday, August 28, 2014 12:56 PM
@Chris_B: my bad. For some reason, I always go to hydro when I'm thinking of water. It's like my "break the brakes" of writing!

@pk386 and ED9man: yep, definitely a short term solution. ED9man details the only truly correct way to do it, but if I'm driving the winter beater for whatever reason mid summer in the PA heat/humidity, I'll do it once to keep from melting into my center console.

Thanks awesome readers for more info!
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