Originally Posted by BigJosh
Originally Posted by Cujet
The 3.5 starts to occasionally idle unevenly after about 4000. I believe that's due to fuel contamination of the oil affecting the idle.
My 15 F150 with 3.5EB has crappy idle at 5K+ miles. OCI at 5% and 6.5K miles. Changing oil today. I use Fram Ultra and PP
Our 2017 Explorer doesn't have the 3.5EB but the 2.3EB. I've used the Motorcraft 910S and the Mobil1 oil filter equivalent. After the short run, ~3,200 mi with the dealer "free" oil change at 2,000 miles I've used Mobil 1 5W-30 up to 7,000 mi OCI and the idle has been smooth as silk all along. Our iOLM would take us to 10,000 miles no matter the weather or type of driving it seems. I'll stick to 7,000-7,500 mile OCI's max except in the winter with lots of remote starts by the wife. I'll reduce that somewhat based upon a winter run of 6200 mile UOA I had done.
Whimsey