Will be having 80k mile service done soon, at 75k, recommended replacing drive belt and having transmission flushed. There's nothing in the maintenance guide about when the drive belt should be replaced nor when to have transmission flushed. Vehicle is well-maintained. Have read on Toyota forums to only have transmission flushed if having transmission issues, which I am not. Forum recommends having transmission fluid drained and replaced, rather than flushed. Anyone have any insight?

Never flush. Only drain

For the belt drive, there is no fixed mileage interval for replacement; instead, it is changed "as needed" based on physical wear and age, though most factory belts typically last between 60,000 and 100,000 miles.

Now a timing belt is old Toyota. A 2020 Highlander should never need replacement as it's a timing chain.

Thanks. Any issues having coolant flushed?

Not that I'm aware of. Someone else may chime in but would not have a problem with coolant.

Where are you taking this to be done?

V6 or hybrid? Two completely different powertrains

I think 75k is a good time to do both. I have a 2022 Highlander with 35k, and I plan to do a transmission fluid flush or drain around 40k, which may be a little early.

I did a transmission flush on my 2002 Silverado pickup at 80,000 and 150,000. I just remember the transmission fluid was filthy at the 150,000 change, while I watched the tech do it. The flush didn't cause any problems, and the transmission actually ran better afterwards.

Also, as a side note, I was talking to the manager of a Kwik Kat shop one day while my oil was being changed. He pointed to a 16 passenger van that was there for service. He said the owner used the van for courier service and brought it in every 10k and had every fluid changed (oil more frequently). He asked me to guess how many miles the van had. It looked fairly new so I figured less than 100k. He said it had just turned 400k miles! So maybe changing the fluids often make a difference.

You can flush the transmission but I would first drop the pan and change the filter in it at minimum. The fluid becomes like liquid sandpaper as it breaks down over time to all the heat cycles and debris (metal shavings) that build up in it so give it a fresh filter.

It's also very critical if you drop the pan or have it flushed, the fluid is refilled properly and verified at operating temperature. If you only top it off when cold, it will be low at operating temperature and will eventually fail. You will then blame yourself for changing the fluid when the whole time it didn't have enough fluid in it.

I know people say if you have 100K plus miles in it don't flush it. Experience has taught me you need to get all that old fluid out as it is doing nothing but causing more wear.

So, change your filter. Run it a few thousand miles then flush it.
My truck has 255k miles on it. I last had it flushed 40k miles ago and plan to change the filter and flush it again this year.

It's a V6. Taking it to the dealership for the work.

I usually take our 2012 Highlander to the dealership for 1 oil change and inspection per year when I get a good coupon. They give a long laundry list of services they recommend. I am always curious what they say.

The other two times per year I will take it to my independent Toyota/Lexus mechanic for an oil change and for them to look it over, and they rarely ever do anything that the dealership tries to sell. Did brake work once, replaced the radiator when they noticed a crack, and replaced a wheel bearing.

aggiedata said:

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Never flush. Only drain

For the belt drive, there is no fixed mileage interval for replacement; instead, it is changed "as needed" based on physical wear and age, though most factory belts typically last between 60,000 and 100,000 miles.

Now a timing belt is old Toyota. A 2020 Highlander should never need replacement as it's a timing chain.

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