Is it normal for an oil boiler to leave a slow drip under the filter?

A slow drip from the filter housing can usually sit a week, but it's a gamble. Those housings leak because the cartridge seal or the top gasket has let go, and sometimes they go from a drip to a weep fast, especally if the oil is cold and thick in the morning. Keep the boiler running if you need heat, but check that tray twice a day and top up the absorbent. If the drip rate picks up or the bowl on top of the filter starts filling, shut the oil supply valve off at the tank and run the boiler off what's in the line until it locks out. Better a no-heat call than a soaked floor. The fix itself is usually cheap, a new element and gasket is a ten minute job for the tech, so don't stress about the bill. A 20 year old boiler with one leak in its life is doing fine.

For the concrete, dish soap alone won't cut it because heating oil soaks into the surface. First thing is getting the bulk off. I pour plain clay cat litter over the whole stained area, grind it in with the bottom of a boot, leave it a day or two, then sweep and repeat until fresh litter comes up mostly clean. Once the residue is thin, scrub with a strong mix of dish soap and hot water using a stiff deck brush, then shop vac or towel it up rather than rinsing it around. You'll probably need two or three rounds. If a ghost stain or smell hangs on, an enzyme cleaner sold for fuel spills works better than anything else I've tried on old oil in porous concrete.

While you wait, put cardboard or a mat over the play area so the kids aren't tracking it, and keep a window cracked down there. Check the whole oil line while you're at it, especially where it runs along the floor and any fittings at the tank. If the filter housing got knocked or corroded, the line fittings nearby are worth a look with a dry paper towel, any fresh wet spot means another call to the tech.

Following this beacuse we had the same thing happen last winter with our tank setup. Ours turned out to be a loose fitting where the pipe meets the filter thing, my husband just snugged it up with a wrench and the drip stopped. Took a few tries to figure out it wasn't the filter itself. Our basement smelled faintly like that for weeks even after cleaning, wich freaked me out with the kids. Does that smell ever fully go away once the oil soaks into the floor, or did you find something that got rid of it for good?

First post here so bear with me. We had somethig similar last year but it turned out to be the burner gasket instead of the filter, which I only figured out after wiping everything down and watching it reappear from a diferent spot. So it might be worth marking where exactly the oil is coming from before the tech shows, saved me a second call. One thing I'm still unsure about though, the oily smell hung around our basement for a good month even after cleaning. Is that normal or does it mean there's still residue I missed?

Been around oil burners since the days when every basement had a drip pan the size of a bathtub under the tank, and honestly those pans caught more than people admit. One thing I used to do when a filter housing wept on me is shut the tank valve, bleed the pressure off through the bleed plug on the housing, and leave it shut til the tech comes. Boiler will run on the line oil for a good while and then lock out on safety, which is exactly what it's meant to do. Beats watching a tray fill up overnight. Mark the date on the new cartridge when it goes in too, that way you know how long these things actually last on your oil.

When mine wept like that I traced it with a strip of paper towel tucked under each fitting along the line, since oil loves to run down the copper and drip off the low point nowhere near the actual leak. Mine turned out to be a weeping compression fitting a foot above the filter, not the filter at all. Worth doing before the tech shows so you can point right at it. For the floor, mechanic's hand cleaner from the auto store worked way better than dish soap for me, scrub it in, let it sit, then rinse light and dry with rags.

Update: took the second poster's advice and checked the line fitting into the filter, gave it a gentle snug with a wrench and the main drip has pretty much stopped. Still getting a light weep around the top of the housing though, so prolly that gasket like the first reply said. Anyone know if those top bolts are easy to overtighten? I don't want to crack anything.