-sources@ (Adds trader comment, details, background)
* Venezuelan oil company would pay the lease with crude
* Companies are running tests, PDVSA would produce more heavy naphtha
* Valero receiving an increasing volume of Venezuelan oil
HOUSTON, Dec 2 (Reuters) - Venezuela's state-run oil company PDVSA and U.S. refiner Valero Energy Corp are running tests to evaluate the restart of five units at the 235,000 barrel per day (bpd) Aruba refinery, which was shut last year over high costs, according to three sources familiar with the situation.
The Aruba refinery was closed in September 2012 when its owner, Valero, reduced its workforce and stopped units at the plant - which cannot convert heavy crudes into light products because of a lack of deep conversion plants.
Since then, Valero has been using the facility in the Caribbean to store its own refined products and also some PDVSA feedstocks, mainly heavy naphtha going out from the 955,000 bpd Paraguana Refining Center (CRP) in western Venezuela, traders with knowledge of the operations told Reuters.
The Aruba refinery would offer PDVSA output of heavy fuels to mix with its own heavy crudes, along with storage space it partially lost in 2012 after several fires in its domestic refining network.
The sources said PDVSA could lease the units from Valero and pay for their use in oil.
"PDVSA is interested in two crude distillation units, one hydrotreater, one hydrocracker and one coker. The company is asking Valero to restart those units to process Venezuelan crude," a source from the refinery told Reuters.
PDVSA, which has well-known cashflow problems, is already leasing tanks in Aruba from Valero and paying for the space with crude sent directly to the United States, the sources added.
Valero declined to comment about possible transactions or current business arrangements, but said it has been using the refinery as a storage terminal and has maintained equipment so the plant could be restarted if a buyer were found. Valero said it buys 100 types of oil, including Venezuelan.
PDVSA did not immediately respond to a request for comment from Reuters.
NEED FOR NAPHTHA
Aruba's prime minister, Mike Eman, told local media last month that the government was interested in the restart of the refinery and that PDVSA would operate it if talks with Valero were successful, but that a deal was still far from being reached.
Previous talks between Valero and companies interested in buying the refinery, including PetroChina and PDVSA, did not succeed.
Having sold several international facilities starting in 2007 and with shipments to many Caribbean countries growing, PDVSA needs an additional place to store its crude and products.
"PDVSA is delivering the crude to Valero at Venezuelan ports and Valero is sending most of it to its refineries in the United States," a trader said.
Valero imported an average of 177,830 bpd of Venezuelan crude this year, a 28.5 percent rise from last year, according to U.S. Energy Information Administration figures updated until August.
The source added that under the agreement terms, Valero is not allowed to resell the Venezuelan crude.
PDVSA and its private partners in Venezuela need to obtain heavy naphtha to mix it with increasing output of heavy crudes in the Orinoco belt and create diluted crude oil (DCO), as production of light crudes that were used to generate blends such as Merey 16 declines.
(Reporting by Marianna Parraga; Editing by Terry Wade and Marguerita Choy)