I haven't gone down and checked my Elantra owners manual. I'm sure that they allow 5w30 up to 100F. I did notice a penchant for thicker oils, however, including 10w40-- kind of a rarity. My dealer uses 5w30 Castrol on all their cars all year around. I get better mileage with 5w30 so am considering keeping it for 9 months a year rather than 3.