I own a 2019 outback that I love. 60k miles. I replaced everything brakes, filters, etc., and oil change (every 6k or less). My experienced mechanic says spark plugs last 100k usually so do they really need replacing at 60k. And the timing belt? Can I visually inspect it for wear? I am thinking of 80k for both - which will get me a couple of years - but that's just guessing. What is the expected cost of this repair at a dealership? (ick) Also, will I invalidate my 100k warranty if I wait. Thanks for any advice.