I ran mostly synblend 5w20 for the first 100k at 5k intervals and had some minor varnish (which has mostly cleared up using synthetic at 3k intervals). I'm sure m1 EP would be fine at 5k.Severe duty for my Hyundai 2.4L GDI engine is 3,750 miles (oil type not mentioned in owner's manual) ... Curious if using M1 5W30 EP if "severe duty" (i.e. suburban driving of various trip lengths) the milage could be extended to 5,000 miles or even 7,500 miles using again M1 5W30 EP with a Fram Ultra oil filter ? Of course , a UOA would confirm but just trying for an educated guess in a well kept engine using a top synthetic oil and oil filter to go past 3,750 miles ? *Also to note , Hyundai Service Manager was emphatic to tell my wife : "Any large city / suburban driving is ALWAYS going to put you in the "severe service" category - whether you get your oil changed here at Hyundai or any where else - just be sure to get it done by 3,750 miles".
At my local Walmart, both Valvoline Advanced/EP are more expensive than the M1 EP.Good replies ... In the end , I'll save the M1 5W30 EP for the PFI vehicles I own . The Hyundai GDI engine will get a mid priced synthetic 5W30 oil (Valvoline Advanced / EP with a Super Tech 10K mile oil filter for a 3,750 ~ 4K mile OCI . It's just not worth it to guess or pay the extra cost of the M1 5W30 EP (which I used once on a long trip) . The Hyundai / Kia 2.4L GDI engines produce a lot of soot and are prone to fuel dilution so again - not worth the risk to stray with too long of an OCI .