A friend got a 2018 Elantra Sport 2.0. I will probably be doing the first oil change on this car. Dealer told her first oil change is due at 3750 miles. After that she had the OLM set at 7000 miles to keep the warranty up. She will cover 7000 miles in about 9 months. Does anyone know if there is a crush washer that needs replacing at the oil service? I've had little experience with Hyundai's before. Also, owner manual says 5w20, 5w30 and 10w30. I will certainly use synthetic but any advice on oil weight? Lastly, any opinions on oil filter choice? Is OEM the best choice for warranty? My personal opinion is to go to Walmart or the like and pick a off the shelf oil filter for the car and 5 quart jug of oil. Thank you in advance for any help you can give me.