Can a protective oil be applied on cedar shingles used for roofing?

Yes, it is possible to apply 2 coats of Osmo UV-Protection-Oil 420 Clear Extra (with biocides) variant on cedar shingles. This product contains UV filters for a level 12 protection (which means UV protection is 12 times higher than untreated wood), but does not contain any stain or pigments. It is important to ensure that the wood is not damp during application and to work in the shade, away from direct sunlight.