My uncle swore by using old motor oil to 'preserve' a cracked block, and I found out why he was dead wrong

So my uncle Bob, who's been turning wrenches since the 70s, told me last winter that if I had a hairline crack in my DT466 block, I should just dump a quart of used 15W-40 in the coolant. Said it would swell the rubber seals and clog the crack right up. I figured he knew his stuff, so I tried it on a 1994 International I was flipping. Well, after about 50 miles, the engine started puking coolant like a geyser. Turns out the oil just mixed with the coolant and turned into this nasty sludge that plugged my radiator core. I spent three days flushing that mess out with a garden hose and a pressure washer at my shop near Birmingham. Has anyone else had a barnyard fix backfire this bad from a so-called 'expert'?

3 comments

3 Comments

grant_allen8518d ago

Read somewhere that the old-timers used to use a bar of soap or even black pepper for small radiator leaks instead of oil. Sounds like your uncle's trick might have been the wrong one for the wrong problem.

jenniferw8218d ago

Oh man, that pepper thing actually worked for me once on my old beater of a truck! I had this tiny pinhole leak in the radiator and was desperate on a road trip, so I dumped in a teaspoon of ground black pepper. It clogged that hole right up and held for like two months until I could afford a proper repair. The soap trick never did me any favors though, just made a mess with bubbles everywhere. I figure if the leak is small enough and you're in a pinch, pepper is way better than nothing at all.

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oliver_morgan18d ago

Did you try running straight water to flush it before the pressure washer hit the radiator?