Two vehicles: 2014 Ford Edge, about 42k on the clock, 3.5L NA engine (no turbo, no DI). Runs fine, has been getting a diet of 5W-20 its whole life with 7500 mile OCI. I use either Mobil 1 or QSUD. Mostly highway driving for its life, and especially now (wife has a 35 mile daily commute, one way). 2018 Ford F-150 5.0 Coyote V8. Starting this year, this engine is dual injeted so it will probably get a little fuel dilution. 2500 miles on the clock, getting factory fill changed at dealer next week (for free, which is why I'm doing it) where they will likely use 5W-20 Motorcraft blend. Will run that to 7500 miles (so a 5000 mile OCI). I will change 5000-6000 mile OCI after (twice per year) with Mobil 1 or QSUD. Mostly city driving with 10-15 trips to northern WI (2 hour drive one way) per year. I also have a fiberglass 16 foot boat that weighs about 2500 pounds that I tow in the summer, but don't go very far with it. My goal: best engine protection, want both of these vehicles to last a long time. I'd also prefer, though it isn't a huge deal, to use the same weight oil for both vehicles. I'm wondering if it would be better to switch to 5W-30? I don't want the oil to be sheared down too much by the end of the OCI and the 30 weight leaves a lot more room. I'm more concerned about the F-150 because of fuel dilution. Also, the upgraded 5.0 for this year increases the sump to 8.8 quarts from the previous 7.7 quarts. That move makes it seem they are worried about heat, even though there is an oil cooler on the engine. From what I have found, tolerances haven't really changed for 50 years so that isn't a good reason for thinner oil. The main reason I've seen to stick with the thinner oil is due to cam timing. Not sure if there is any truth to this? I've seen a lot of people on the F-150 forum who have switched their 5.0 Coyote (before it was dual injected) to 5W-30 or even 5W-40. There seems to be a lot of people who think that the lighter oil is only recommended for CAFE. As evidence they point to the 6.2L recommendation being changed to 5W-30, when it had been 5W-20 (that engine is now only in the Superduty, not the F-150, so it it exempt now from CAFE). Also they cite some of Ford's engines (and other company's) recommending heavier oil in other countries that don't have CAFE, for the exact same engine. The 3.5L Ecoboost used to recommend 5W-20 until Ford apparently found that wasn't enough protection and now recommend 5W-30. There are also a few quotes mentioned which are supposedly from former Ford engineers that say 5W-30 is better for engine protection. I have a pretty big stash of 5W-20 that I could return or exchange for 5W-30. Even the Edge is in manufacturer powertrain warranty for another two years or 18k miles. I'm wondering if it would be smart to get an oil sample analysis done on both at the end of the next OCI to see shearing and (in the truck) fuel dilution? Then go from there. Thoughts?