java.lang.NoClassDefFoundError: buildcraft/core/ILiquidContainer
        at TileEntityOilFabricator.b_(TileEntityOilFabricator.java:77)
        at rv.l(World.java:1472)
        at net.minecraft.client.Minecraft.k(SourceFile:1384)
        at net.minecraft.client.Minecraft.run(SourceFile:666)
        at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: buildcraft.core.ILiquidContainer
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 5 more