From a table on the net: ATF density at 20C (~ room temp) = 0.8655, density at 90C (~ 194F) = 0.8205. I don’t know about the Highlander’s fluid but imagine it’s similar. At this density difference, fluid volume will expand ~ 5.5% from cold to hot, amounting about 1 pt. for a complete change on a 10qt. capacity system, which is approximately the difference between “add” and “full” on many AT dipsticks (it depends on the geometry of the transmission case), and the reason for some dipsticks having cold and hot level markings. One can see the same cold/hot distinction on PS fluid reservoirs. The absolute difference will be proportionally less for a partial drain and fill. Does this difference matter, who knows?
You won’t get 10 quarts out of the pan on a drain and fill. You’ll get about half the capacity.
I really don’t think the difference in volume of 5 qts atf hot vs 5 qts atf cold will matter.
It has t mattered yet, for me at least. Will let you know in another 80k when I reach 200k. Beyond 200k, it’s all gravy. 
Read my next to last sentence.
I did. I’m on the same page. I’m just thinking I can probably get the volume added back as close (even measuring hot vs cold) as a tech can with a scanner reading temp and adding back until overflow plug goes from a stream to a trickle (or however the service manual describes the procedure if there’s no dipstick, I don’t recall). Point being, the only thing that sounds precise in the service manual is the temp reading with the scan tool. The rest is fairly objective. Or subjective. I forgot which was the proper term. I’ve worked 10 hours on a scrapyard today, mowed the grass, and had a few beers. And I’m glad it’s a paid holiday weekend. Like manna from heaven. Hope you have a good weekend!
Sounds good, just put beer and ATF in the right places.
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The stand pipe in the pan that sets the fluid level is precise, it sets the fluid at the same depth each time when checked at the right temperature. With a dipstick the “normal” range between add and full was about 1 1/2"
Well I have the Acura AWD V6 and I think you are way overdue. Acura insisted that the differential should be changed at the first 10,000 miles, then with the transmission after that. The transmission, transfer case and differential were then changed at 30,000. So I would do all three pronto. I think it cost me under $200 at the dealer. I can’t believe the maintenance needs of Toyota and Acura would be that much different and they were very clear on doing the differential at 10,000.
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I own a 14 V6 Highlander with over 120k miles.
Toyota’s recommended fluid change intervals are probably fine for most people who sell their vehicle before it reaches 150k miles. I’m not one of them.
Toyota recommends 10k mile oil change interval - I do mine every 5k miles.
Toyota says tranny fluid is forever - I change mine every 50k miles.
Not sure what the differential fluid or transfer change interval is, but I change mine every 50k miles.
Quoting an old member who use to be on this site.
“Are you trying to get the most out of your fluids or the parts they are protecting?”
We keep our our vehicles well over 300k miles and I’ve NEVER EVER had a mechanical issue with any drive-train part.
With the tranny fluid…make sure you use the right fluid. Not too many make a WS fluid. And the non Toyota labeled fluids are just as expensive as Toyota’s WS fluid.
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75k, just do it. Relatively cheap insurance, wont have to deal with it again until 150.
All of this very spot on with my feelings on the matter.
I would strictly follow the owners manual . that is Toyotas guide and what they will follow and what you will have to prove you followed if something catastrophic happens .
The recommendations in your owners manual were made by the people who designed and tested every component in your vehicle. They spent millions to come up with the various intervals.
BUT, they are only concerned with the first owner. They don’t make any money when you trade your vehicle in or sell it. New car buyers keep their cars an average of 11 years and about 150k miles, last time I heard these stats. It may have changed since then but I doubt it changed by much.
They also base their recommendations on average conditions. That being climate etc. They do have a different schedule for severe conditions and driving.
The dealer has not spent all this time and money to determine the best schedule, but in their defense, they do know the local conditions and if they are performing all your maintenance, they can spot conditions unique to your driving conditions and make some recommendations based on that. They may also recommend a change if you have either a history or have indicated that you will keep this vehicle longer than average, which you have done here.
If the variation in the schedule makes since to you, and I think that in your case it probably does, they you may want to follow their advice.
BTW, the transfer case and the front differential are very close to the transmission so they will get much hotter than the rear differential. Heat is the main enemy of oil. The rear differential may not really need to be changed as it remains much cooler, but should be checked at least.
The mfr’s maintenance schedule should be considered as the minimum that is done in order to avoid mechanical problems. More frequent maintenance is better, and if somebody is the second or third owner of a vehicle, he/she should hope/pray that the first owner did more than just the minimum.
The service intervals for normal relate also back to normal ownership period which is 8 years/150,000 miles. What is your future plans for keep the vehicle. Trying to hit 200k+ or just maybe 150k? If 150k I’d leave it be.
Here’s my thoughts . . .
Maintain every vehicle at least per the severe schedule maintenance schedule . . . the possible exception being the automatic transmission, cvt, etc., where the severe service schedule may not be enough, if you’re planning on keep the car awhile
Because what if life changes, and you’re forced to keep that car past 150K and drive it indefinitely . . . ?
Accidents, health problems, death in the family, laid off from work due to the company downsizing, etc.
If one of those scenarios were to happen, you’d be wise to have a vehicle that’s already been very well maintained, and can last a few more years, versus one where your idea of well maintained is treating it to an occasional detailing
I know only one person who keeps a car beyond 10 years or 100,000 miles, and he is so frugal that when we walk down the street, the birds on the telephone wires all call him…cheep, cheep cheep.
I wish I belonged to such a well-heeled community as yours . . .
In my neck of the woods, keeping a car beyond 10yrs/100K is very common
The birds here are constantly chirping 
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Admittedly, most of the folks I know are either white-collar management or professionals.
Just because someone keeps a vehicle for a long period of time does not have anything to do with ’ Frugal ’ . It may just serve it purpose or has been reliable enough that there seems no reason to replace it . I had one for 18 years , one for 16 years and one in my garage now that is 10 years old.
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I have maintained the vehicles to severe schedule and also the bare minimum normal schedule. Both seem to last 13yrs / 200k plus some with an unrelated expensive repair being the demise where I move on.
People mention change water pumps with timing belts (always turn down) but I yet to have one fail over 10 timing belt changes across different vehicles. I do the tensioner typically though at first change.
So thankful for modern cars avoiding timing belts except Honda V6 including my 200k 07 MDX.