UPDATE: Reviews section refreshed, redesigned, searchable: Go take a look
Can [url= http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_204265_langId_-1_categoryId_255218 ]this[/url] be used as an alternative to Shimano Mineral oil?
that looks like the stuff I've used before.
It does work but is a bit thicker than the Shimano stuff. Not sure if it makes any difference in practice other than it seems a little more tricky to get a decent bleed in cold weather.
To be honest I would just stick with the Shimano as CRC are doing 1L bottles for a fantastic price at the moment: http://www.chainreactioncycles.com/Models.aspx?ModelID=5620&utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom
I've used citroen LHM many times on some XT brakes with no issues at all.
