OK - I'm good at changing the oil (every 5k) but not the transmission fluid or other types (differential, etc...)

I have 216k miles on my 04 4wd 4.0 4runner that runs great. I had my mechanic look at the transmission fluid and he says it looks good and he would change it. He says he's seen more transmission trouble after people replace than before. I've had similar problems as well. I was having a strange vibration in my 04 Impala at around 100k miles. I did the transmission fluid change and the Impala would never shift into gear afterwards and I had to buy a new transmission. (I bought it at 170k and my friend had before at 100k, and he didn't change the transmission fluid either)

Anyway - after reading much in the forum, I'm thinking of having all the fluids changed and running synthetics (I run 5w30 synthetic oil).

Just curious of what people of found or recommend for transmission, differential, etc... Thanks!

BTW - I've also had a lot of valve noise this summer, which it is super hot. Anyone changed oil type or manufacture and had the noise disappear?

PS
I'm going to get an oil analysis after this next oil change this week. Curious to see what it shows with over 200k on the engine.

I read on here that for a 4runner with that many miles it's better to 'drain and fill' rather than 'flush' the atf.
Flushing the transmission of a high mileage truck will dislodge things that were keeping the truck together.
Can someone verify this? My 3rd gen has about 200 on it and I am in the same position as Moore

That's somewhat true if the tranny has problems that were NEVER dealt with.

s1moore1s: Did you get your truck new or used?

If used: try to get a service history of the truck. MAYBE the tranny fluid HAS been changed so you are definitely due (some say it doesn't have to be changed, but that is nonsense, every 100K).
If new: (and never has been changed), and your mechanic says it's still looks good, then yes, get it changed (no signs of damage).

Changing the tranny (if yours is sealed) is a b**ch to do. My dealer wants $170 for the job which I'll gladly pay (let them burn there hands off). The front/rear diffs and transfer case are arguably EASIER to do then changing the engine oil. I use Mobile1 everywhere (except tranny)

I change my oil every 5K and change the rest of the fluids (brake, steering, transmission, transfer case, differential, radiator, etc.) every 30K. My 4R purrs and runs like a champ.

I have a sealed transmission as well, and 65K miles. I called the dealership and they said to not worry about it till 100K. So I asked how much and they said $350...yikes!!