New here, nice forum!
I drive all highway miles in my 2000 avalon xls. I bought the car with 96k miles on it and I've put 40k on it, so it now has 136k miles on it.
I've changed the oil anywhere from 5k-7500 mile intervals. With all highway miles at consistent speeds mostly, is this ok, or should I switch to every 3k miles?
I've just been reading about engine sludge problems if you don't change the oil enough. My car doesn't burn any oil at all. When I do check the oil after 5k miles it is still pretty clean and the level is the same place as when I first changed it. Am I ok with my current interval? I use Castrol GTX 5w30 oil and fram filters.