I have a choice I'm stuck with. My wife's 1999 4 Runner (3.4) has 135,000 miles and runs great. My 20001 Tundra (4.7) has 110,000 and also runs like a top. I've used Mobil 1 5w30 and Mobil 1 M-102 oil filters on both since new. In each, after turning 100,000 miles, I started changing the oil every 5,000 miles instaed of every 7,500 miles.
As a precaution, I'm wondering if I need to switch to Mobil's High Mileage versions for valve seal and engine extra protection. The 5w30 version of Mobil 1 High Mileage synthetic is hard to find. The 10w30 High Milage version is more common and easy to find. The manual suggest 5w30 for all temps and 10w30 for 0 degees and up.
In older engines without any oil usage issues (both seem not to use any oil), would using Mobil 1 10w30 High Milage cause issues except in winter (below 0)?