I have always been a "buy what oil is on sale and a NAPA (Wix) filter" kind of guy. But now that I have two newer cars, I am a bit more concerned about longevity and making sure to comply with my warranty. So I would like to know what oil and filter you would choose for my cars. (Please note that I do respect everyone's educated opinion, but am very flighty and may just do whatever I want anyway...) Car 1: 2015 Kia Soul, 1.6 GDI, 18,XXX miles. Oil changed at 2.5K, 5K, 10K, 15K, and 18K with 5W-20 Pennzoil Platinum and OEM filter. This car is driven by my wife to and from work (10 miles and 20 minutes each way). Occasional short shopping trips. Very few highway miles. Ohio weather so -20F in the winter up to 95F in the summer. My wife really likes her car, so will likely keep it past the 10/100 warranty. Car 2: 2018 Hyundai Elantra, 2.0 MPI, 1,XXX miles. 15 mile commute to work. Highway trips most weekends. Due to expensive bells and whistles (Nav, lane departure, headlights that turn), I may or may not keep this car past the bumper to bumper 5/60 warranty. My initial thoughts are... Change the Soul to 5W-30 due to possible fuel dilution. Change the Soul to 3,000/6 month OCI from 5,000 to reduce dilution and carbon deposits. I have no idea what to do with the Elantra. Thinking I should do severe duty schedule which is 3,750 OCI for warranty purposes. I have 10 quarts of 5W-20 Pennzoil Ultra Platinum, 6 quarts of 5W-20 Castrol Edge Gold, and 1.5 quarts 5W-20 Pennzoil Platinum sitting around. That would take care of the first 4 oil changes if I switch the Soul to 5W-30. So... Seems like there are better filters for this car than the factory filters. What filter would you use? What oil will work best in a GDI car that sees little use? Ultra Platinum claims to clean things up, true or hype? Synthetic, blend, or conventional for the Elantra? Normally purchase Pennzoil products from Amazon with a $10 rebate, about $15 per jug of syn delivered. No loyalties to any brand beyond that. Not sure if this is too much information or not enough, but thanks for any help you can give!