I have an old oil cooler of an old Volkswagen engine (the type where the oil itself is cooled, and uses no water) stained with decades of usage. If I pass water through it, it comes out clear, but if I pass a clear oil through it, it comes out black.

What is the best method to clean it that uses cheap and easy to find substances? I want to use it to cool clean mineral oil, I want my oil to remain clean.

My father suggested to pass mineral oil through it until what comes out is clean, then install it in the system, but that would be horribly expensive and messy, and I would need to discard all that dirty oil properly afterwards. I myself thought of using gasoline, filling halfways, shakink and discarding, until clean enough, but although that would be less expensive, it would be as messy as the first option, and probably dangerous. My sister suggested using water and kitchen wash-up liquid. That would be much less messier, because it is water soluble, but I don know the proportion of water and kitchen detergent tI must use for it to be effective. My last idea was to use some grese remover like Ajax, that would not be so.much messy, either.

So, what do you suggest?

  • $\begingroup$ Car repair shops often have a solvent wash station. The ones I have seen use kerosene, paraffin, white spirit or diesel to cut through the grime. You could locate shop in your area and ask if you can spend a little while at their wash station, they may have a similar radiator with just a broken bracket lying around they can offer you that is otherwise unused. $\endgroup$
    – KalleMP
    Mar 7, 2016 at 19:41

2 Answers 2


In terms of inexpensive, safe, and a little polar to move oxidation products, I'd try soaking in and flushing with hot soybean oil (replace elastomer hoses and seals). Then flush with kerosene (odorless white spirits, hardware store paint section), then blow out with compressed air.

Carburetor cleaner was mixed cresols - dangerousy on skin (heavy gloves), but great against deposits. If it is really nasty in there, I'd go for gun bore cleaner soaking, specifically Ed's Red without the lanolin and substituting MEK (methyl ethyl ketone) for the acetone to lower flammability. At the end, blow it out, flush with kerosene, blow it out.

Contain all wastes. Beware of skin contact (gloves) . Do not breath the fumes (ventilation, and maybe a charcoal latex paint mask, then discard). Eye protection (goggles). VAPORS ARE FLAMMABLE AND HEAVIER THAN AIR.

Ed's Red Gun Bore Cleaner (wear gloves!)

1 part Dexron II, IIe or III ATF, GM Spec. D-20265 or later.
1 part Kerosene - deodorized, K1 (can be Kroil or WD-40)
1 part Aliphatic Mineral Spirits, Fed. Spec. TT-T-2981F, CAS #64741-49-9, or may substitute "Stoddard Solvent", CAS #8052-41-3, or equivalent, (aka "Varsol")
1 part Acetone, CAS #67-64-1.
1 lb anhydrous lanolin or Lanolin, Modified, Topical Lubricant.

Note that Ed's Red is rapid death to plastics, polymers, varnishes, paints, and coatings.

  • 1
    $\begingroup$ The lanolin is persistent, to deter gun rusting. That, of course, is not your problem. Clean, lubricate, protect is the gun challenge. Weapon Shield is remarkably good - but you could buy another cooler for the cost of using it in this application. $\endgroup$
    – Uncle Al
    Feb 10, 2014 at 23:24

You can use kerosene instead of gasoline in a well ventilated area, but your best bet will probably be grease remover. Trying different things will let you know what is effective, and each pass will clean the cooler a bit. Just don't leave it a long time with water, as that might rust it.


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