You really should run a nice M1 0/40 in these 4.0 engines..your missing a wonderful experience in any climate, give it a try.
These will run forever on anything.
At 10,300 miles, I just changed the oil for the 2nd time on ours.
1st OCI was M1-AP 0W-20, at around 2900 miles. Went with that because id gotten a bunch of that oil for $2/qt in late 2019 during the Auto Zone clearance. And, it was winter.
This time, I went with M1-EP 10W-30 ($9.47 plus tax for a 5-quart jug after rebate). Definitely smoothed the engine a bit, especially helped with the buzziness it had at >4500 RPM.
I like M1 oils. Nice that it’s almost never necessary to pay full price for them!
I’d run other oils if they’d run good rebates on them like M1 does.
I also still have enough Valvoline Modern Engine 0W-20 and M1-AP 0W-20 (also obtained during the AZ clearance) for a few OCIs. And I’ll use it up for winter time oil changes. Got all that because the wife had a Civic 1.5T at the time (and I couldn’t turn down all that good oil for 2 bucks a qt).
However, if specifically buying oil for the 4Runner (or my Tacoma), the thinnest I’d go would be a 30 grade.
If I could get a great deal on it, I’d absolutely run M1 0W-40 in either of my trucks.