I purchased our Acura MDX 3.7L. Used. The previous owner changed the oil every 5k with M1 5/20. She did this religiously she owned it from the time it was new until 99k miles. I've ran Castrol 0/40, PP 5/30 now PP 10/30. Awesome car. when I look inside the oil fill hole straight into the valve cover I can see no sludge and shiny aluminum on the cylinder head, I do see some varnish. (brown). My question is with this change Pennzoil Platinum 5/30 SN+. The oil was almost black at 2500 miles. Is this oil doing some serious cleaning up? It didn't do this with the Castrol 0/40 until around 5k miles. I changed the 5/30 out. Now running the PP (SN) 10/30; btw. Using a fram ultra synthetic filter. Previously I've used the Purolator boss. The Honda OLM at 15% is around 5500 miles. M-F it's all short trip. The wife commute round trip is 5 miles. I use it on Saturday nights for Lyft and Uber and usually put on about 500 miles. I know what some say, I make 6-700 on a Saturday night. Yes I found a little gold mine where there is few drivers and high demands. If this is really doing some serious cleaning power maybe I'll leave the oci at 3000 until the oil is still clean at that mileage