When to Replace Engine and Inverter Coolant?

It's weird, must be a different publication. The date says 1/10 which I gather to be Jan 2010 (yellow highlight):



There's that footnote, which says to read the relevant Explanation of Maintenance Items, which turn says nothing about changing the dates/distances:



I'll attach the whole thing.

 

I just follow the expert's advise....the service manual recommendations.

 

Yeah besides being out of date it's also out to lunch: practically every interval mentions engine/inverter coolant. And the footnote 3 on page 51 seems orphaned, nothing seems to ref to it. Guess that got fixed on newer version. I'm throwing in the towel.

 

My 2010 Prius just turned 100,000 with no repairs yet. I will be changing the engine and the inverter coolant soon. I was also told to change the transaxle fluid too.

 

Oh, do the transaxle fluid asap. An early change, say after a year or two, 20~30k miles, is good. Then stretch the interval.

 

Why is the Toyota recommended change interval for the engine 120 months and the inverter coolant at 150 months? I thought the coolant turns acidic over time...why would the inverter turn less acidic than the engine coolant over time?

I just finished my EGR circuit and was about to replace both engine and inverter coolant at 111,000 miles as it seemed logical to get both out of the way.

 

In the inverter circuit, the coolant temperature is significantly lower (140 °F) 60 °C than in the engine circuit (203 °F) 95 °C

.

 

Agree the inverter does not get as hot and is less likely to get contaminated. However the inverter will code at 149f and internal temps fluctuate quickly so effective coolant and water pumps are still essential.


Why 100,000 on the engine coolant? Likely because the best premixed Toyota coolant is advertised as Super Long Life. If you use their only other option, Long Life concentrated coolant, it is half the miles. Possibly because Toyota does not trust people to mix properly with distilled water.

 

You guys bring up some good points - the coolant is also exposed to more continents in the engine circuit so I'm sure that adds to the breakdown. Interesting to hear about the Toyota Super Long Life coolant vs the Long Life.

Here is what my engine coolant looked like at 111k (inverter coolant is still bright pink):

like a bright orange sunset.

 

How hot does the engine get? 1000 degrees, or more?
How hot does the inverter get? A few hundred?

That's the difference.