SINGAPORE, April 19 (Reuters) - The Asia-Pacific crude market was mixed as light sweets traded lower on ample supply while Malaysian medium grades rose on improved gasoil margins and robust demand from oil majors. * TENDERS - Russia's Sakhalin Energy sold 730,000 barrels of light sweet Vityaz crude for June loading via a monthly tender at a lower premium than the previous month, on ample supply, traders said. The cargo was sold at $5.10 to $5.30 a barrel above Dubai quotes to a Japanese buyer, likely Petro-Diamond, they said. Following the tender, Sakhalin Energy sold another three cargoes at similar premiums to SK Energy, Sinochem and an oil major, the sources said. - Vietnam's PV Oil sold two 200,000-barrel cargoes of Rang Dong crude for June loading at lower premiums than the previous month as ample supply weighed on sentiment, traders said. A cargo to load on June 1-7 was sold to a trader at about 50 cents a barrel above the Minas formula, while a second cargo for June 22-28 was sold to an oil major at a premium of about $3 a barrel, they said. The buyers were not immediately known. - Malaysia's Petronas sold a cargo of Labuan crude for June loading at a slightly higher premium than the previous month, traders said. The deal reflected firm demand for the distillates-rich Labuan as other grades produced in the region were sold at lower premiums for June versus May on ample supply. The producer sold 300,000 barrels of Labuan for June 17-23 loading at a premium of about $8.50 a barrel to dated Brent, traders said. - Petronas sold 300,000 barrels of Penara crude for June loading at firm premiums, reflecting robust demand for the grade, traders said. The cargo, to load between June 1-7, was sold to Shell at a premium of just below $5 a barrel to dated Brent, they said. Demand for the medium-sweet Penara crude has been strong in Asia, particularly from Japan, as it is one of the approved grades for burning at Japanese oil-fired power plants. - Russia's TNK-BP offered 730,000 barrels of ESPO for June 5-10 loading. The tender will close on April 20 with bids valid until April 23. - Indonesia's Petral issued a tender seeking sweet crude for July delivery. Offers are to be submitted on April 24 and will stay valid until a day later. * MARKET NEWS - Japan will slash its crude purchases from Iran by almost 80 percent in April compared to the first two months of the year as buyers comply with Western sanctions, trade sources said. - Woodside is gearing up its Pluto LNG project to load its first export cargoes in the "coming days," Woodside said in its March quarter production report on Thursday. CRUDE Price Prev Change JUNE Brent 118.69 118.46 0.23 JUNE Brent/Dubai EFS DUB-EFS-1M 3.93 3.60 0.33 PRODUCT CRACKS Price Prev Change MAY fuel oil crack -4.09 -4.51 0.42 MAY gasoil crack 16.75 16.27 0.48 MAY naphtha crack -6.38 -6.13 -0.26 COMPLEX REFINERY MARGINS Today 8.21 Last 5 days 8.02 Last 365 days 7.69

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