concrete casting / release agent?


Hi all,
I need to do some repairs to the concrete surrounding our basement wood chute; the concrete forming the chute has settled a little over the years, resulting in gaps on the outside of the house between the chute and the basement wall which I want to fill in.
Couple of questions:
1) Will used engine oil work as a release agent between the concrete and wooden mold? I've got some laying around that was heading for disposal.
2) How long do molds need to be left in place? Presumably not the whole duration of the curing process - but 24 hours? 48? (I've only ever used concrete for doing post-work before, where the post-hole forms the mold)
Due to the fact that what I need to fill in on each side of the chute is about 3' high, 4" wide, and a couple of inches deep at the top (tapering to 0 at the bottom), I suspect that I need to fill as much as I can with concrete, then make good with mortar afterwards - concrete alone won't pour nicely into such a small space (none of it's really visible from the outside, so it doesn't need to be cosmetically perfect).
I bet it'll ever be 100% water-tight, but anything's better than a 2" gap that visibly leaks water every time it rains :-)
cheers
Jules
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Jules Richardson wrote:

use an epoxy/sand slurry (epoxy cement if you will) for patching and repairing old concrete. Cover molds with grease or thick plastic for 'release'. Might fill 1/2 the crack with that spray foam in a can. The epoxy/sand the top inch or two.
paul
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On Mon, 26 Jul 2010 16:38:51 +0000 (UTC), Jules Richardson

Yes. So will diesel fuel, that is easily brushed on the wood.
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