2011 Sienna coolant change, drain and refill ?

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Van has just over 90k miles, almost 8 years old, coolant has never been changed. Planning to change the coolant this weekend before a long trip to FL. Should I just drain and refill? I have 3 gallons of Pentofrost A4 ready in the garage along with a couple gallons of distilled water. Or should I drain and refill with distilled water and run the car to flush out the remaining coolant? I see Chrisfix videos on youtube and he flush the system with distilled water a couple of times before refilling with coolant. Is that really necessary?
 
Modern coolants don't degrade like the old formulas. If the coolant in the radiator looks clean, I would just drain and refill as long as the Pentofrost is compatible. If not, flush with distilled water and mix the new 60-40 and run it.
 
I did a drain and fill on my wifes yaris at 100K. The original coolant was a little darker but clean so I didnt feel like a distilled water flush was necessary. I did however use the same factory coolant that was in there. I might do a distilled flush if I was changing over coolant brands.
 
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Originally Posted By: mister_two
... I see Chrisfix videos on youtube and he flush the system with distilled water a couple of times before refilling with coolant. Is that really necessary?

I just depends on what you want to do and are comfortable with. Yes, doing a distilled flush series before using new AF will give you the longer/full recommended service interval.

The issue with that is, A4 like majority oem Asian AFs is a premix. Unless you plan on finding and using the block drain(s) you'll have a difficult time getting a 50% AF concentration. Depending on drain location(s) it can be a pain. Other way is to run the new A4 premix through the system with d&fs until you reach 50% concentration as tested by and AF tester/hydrometer. That is a wasteful process.

My advice, just do a radiator d&f with A4 premix and shorten up the service interval. Do it again in 2-3 years.
 
Just do a drain and fill unless you see flotsam draining out of the radiator. Japanese cooling systems typically run pretty clean if you stick to OEM or pHOAT coolants.
 
I have a method that I consider to be a poor boy flush. I drain the coolant from the rad. I close the drain valve (or in a newer car, put the lower rad hose back on). I fill the rad with distilled water (it's cheap). I then take it for a ride and turn the heater on until the engine is at operating temp and the heater is blowing hot. I go home, have a beer and let it cool off. I then drain the rad again. Now, if I feel like it, I dump in distilled water again and repeat. When I drain the rad for the third time it's pretty clear. I then put in the full strength coolant equal to about 60% of the system and top off with distilled water. I then take it for another ride to get rig of any air bubbles and touch up the tank with 50/50. I have on hand a few extra empty jugs to store the the coolant from the three times I drained the radiator. I dispose of the fluid at the local recycle place. I never bother with the block drains and I don't bother with a flush compound but I guess I could. Done for 5 years. My oldest car has 17 years on it, and has had 3 poor boy flushes like this. Still on the original radiator and water pump.
 
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If it's Toyota pink it's good for 150k. But I would do it anyways at 100k and I would not swap it out with something else. Toyota makes the best coolant on the market IMHO
 
For Toyota, you just need to do a drain and fill.

The Toyota coolant is silicate free.
 
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Drain/fill is all I've ever done with my 2002 Tacoma since new. I used to use red, now I use the pink. I've yet to touch the cooling system on my 2012 Highlander, but that's all I plan to do to it too.
 
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