Last summer I changed the oil on a lot of vehicles to a mixed blend of HDEO and PCMO, all within the same family. These HDEO and PCMO blended mixes are not used in cars or vehicles under warranty. They are not used in modern vehicles since most of the oil is API-SM, CJ-4 for the HDEO.
I plan to do the same this coming summer on some of the cars that I change oil.
I had nothing but compliments on how well their engines ran in the heat of summer in severe NYC driving.
15w-40 and some synthetic or conventional PCMO at 5w20 or 5w30 in a mixed blend of 50/50 for the heat of summer seems to be the ticket.
When I changed the oil out, at the end of summer and before the winter, on these vehicles the oil was nice and dirty....lol....the detergent package in the HDEO really loosened up any dirt and liquefied any build up while holding it in suspension.
I'm planning on running another round of HDEO, API-SM, CJ-4 oils this coming summer. I have accumulated quite a stash of Shell Rotella T3, Castrol Tection Extra,(compliments of the Kmart clearance) and Mobil Delvac Super,(Compliments of Mayport NAS, Commissary) all in 15w40.
I plan to use Mobil 1, PCMO with the Delvac, Formula Shell in conventional and synthetic with the Rotella and Castrol Syntec with the Castrol Tection.
These mixed blends, within the same family, should really help the engines to run smooth while cleaning up any build up from stop and go, short trip, excessive idling and excessive summer heat.