At first, Diesel tested crude oil from Pechelbronn, but soon replaced it with petrol and kerosine, because crude oil proved to be too viscous, with the main testing fuel for the Diesel engine being kerosine. In addition to that, Diesel experimented with different types of lamp oil from various sources, as well as different types of petrol and ligroin, which all worked well as Diesel engine fuels. Later, Diesel also tested coal tar creosote, paraffin oil, crude oil, gasoil, and fuel oil, which eventually worked as well. In Scotland and France, shale oil was used as fuel for the first 1898 production Diesel engines because other fuels were too expensive. In 1900, the French Otto society built a Diesel engine for the use with crude oil, which was exhibited at the 1900 Paris Exposition and the 1911 World's Fair in Paris. The engine actually ran on peanut oil instead of crude oil, and no modifications were necessary for peanut oil operation.