An increasing number of forum members are touting the virtues of using Synthetic Euro Oils (i.e. M1 ESP 5W30 , Pennzoil Platinum Euro 5W30 and Castrol EDGE LL 5W30) as being superior for American bought / branded GDI engines . So , do these Euro synthetic 5W30 oils offer any significant advantage to current SP rated D1 / Gen 2 level of American synthetic oils currently used in modern GDI engine applications ? Do the Euro low ash synthetic oils perform well with American gasolines ? ... The only thing that jumps out in the Euro synthetic oil specs for 5W30 is that they are thicker 30W oils (pushing 12 cSt) and with an HTHS at 3.5 versus the lower 3.0 ~ 3.2 of American 5W30 SP / D1 Gen 2 oils . Lastly , is there some magic Euro formulation proven to be superior for preventing GDI engine intake valve deposits versus the American branded synthetic 5W30 SP / D1 Gen 2 synthetic 5W30 oils ? Currently I use synthetic Valvoline Advanced 5W30 SP / D1 Gen 2 rated oil for a OCI of < 5,000 miles OCI in a Hyundai 2.4L (non - turbo) engine and I want to know if I can do better by using the Euro synthetic 5W30 oils with all the Euro car engine specs met in my Korean Hyundai Sonata ? Thanks in advance for the FACTS .