Shale oil extraction Energy estimates that the "ex-situ" processing would be economic at sustained average world oil prices above $54 per barrel and "in-situ" processing would be economic at prices above $35 per barrel. These estimates assume a return rate of 15%. Royal Dutch Shell announced in 2006 that its Shell ICP technology would realize a profit when crude oil prices are higher than $30 per barrel ($190/m), while some technologies at full-scale production assert profitability at oil prices even lower than $20 per barrel ($130/m). To increase the efficiency of oil shale retorting and by this the viability of the shale oil
Motor oil that flows better, allowing fresh oil in its place sooner. Cold weather has a thickening effect on conventional oil, and this is one reason lighter weight oils are manufacturer recommended in places with cold winters. Motor oil changes are usually scheduled based on the time in service or the distance that the vehicle has traveled. These are rough indications of the real factors that control when an oil change is appropriate, which include how long the oil has been run at elevated temperatures, how many heating cycles the engine has been through, and how hard the engine has worked. The