Lexus says to replace the timing belt at 90,000 miles only in "severe operating conditions" Unless we use these at taxi cabs, few owners meet this criteria - yet the dealers seem to stick to the 90K standard - probably for revenue. But the question Lexus does not answer - "if you don't do it at 90,000 miles -when do you have to replace the timing belt?" Never?? 120,000? When? If anyone has had any guidance on this I would be interested!