4. INVENTORIES

Inventories include the following:

	March 31, 2016		December 31, 2015
	(thousands of dollars)
Raw material	$	2,213	$	2,905
Work in process		63		56
Finished products		15,049		12,843
Total inventory	$	17,325	$	15,804

The difference between the calculated value of inventory under the FIFO and LIFO bases generates either a recorded LIFO reserve (i.e., where FIFO value exceeds the LIFO value) or an unrecorded negative LIFO reserve (i.e., where LIFO value exceeds the FIFO value). In the latter case, in order to ensure that inventory is reported at the lower of cost or market and in accordance with ASC 330-10, we do not increase the stated value of our inventory to the LIFO value.

At March 31, 2016, and December 31, 2015, LIFO value of petrochemical inventory exceeded FIFO; therefore, in accordance with the above policy, no LIFO reserve was recorded.

Inventory serves as collateral for our amended and restated loan agreement (see Note 8).

Inventory included petrochemical products in transit valued at approximately $1.6 million and $2.7 million at March 31, 2016, and December 31, 2015, respectively.