Just 2 weeks ago I went through this exact issue in my Rav4 (112k), had switched to 0w30 and 5w30 HM but the leak slowly got worse over time. I finally bit the bullet and replaced the timing cover. And it ain't cheap once you add in all the "may as well do's" like serpentine belt, replace pulleys and tensioners, etc. The vehicle is otherwise is such great shape it was worth it to see if I can get another 3-5 yrs out it without more major repairs.
FWIW the issue for me is I would notice a hot or burning oil smell in my garage after I parked it. But I could never find anything actually dripping. Chased it around for prob 2-3 yrs, replaced pcv, switched oils, etc, was driving me crazy. Finally I noticed an actual drip off the oil pan, which I traced up to the pulley area and voila apparently it was the timing over. They didn't have to remove the engine, but they had to remove a whole bunch of other things.
FWIW the issue for me is I would notice a hot or burning oil smell in my garage after I parked it. But I could never find anything actually dripping. Chased it around for prob 2-3 yrs, replaced pcv, switched oils, etc, was driving me crazy. Finally I noticed an actual drip off the oil pan, which I traced up to the pulley area and voila apparently it was the timing over. They didn't have to remove the engine, but they had to remove a whole bunch of other things.