Walther de Nijs, Executive Director of LISO (Local Initiatives Support Organisation) wrote from Tanzania.
“With interest I read your article on Used Motor Oil in EDN 93. I would like to share with you that used engine oil is a commodity here, but for a different purpose than you described. Here we use it to “paint” poles for a fence or poles for houses (mud hut construction) (with the oil definitely slowly leaking into the environment, sorry) or to “paint” the roofing timbers. The idea is that the oil is so dirty that termites and other insects hate it like nothing else. When put on the poles that are used for a fence, it wears off and after some time (depending on soil humidity I assume) it wears off to the extent that the poles become attractive again for termites and fungi. But it helps. On the roofing timbers I don’t think there are environment hazards; it certainly prevents your timber from being eaten and, consequently, your roof being blown away by storm. I used it in my house, my cow stable and in our office. Works perfectly, no insects chewing away on the timber!
“After changing oil in a car, the mechanic always requests to keep the oil. He sells it (or we ourselves do, now that we found out that it has a price) for some US$ 4.50 for a 5 liter container.”