Used Gen4 Pre-purchase: TSB's, Caveats, Recommendations

Contrary to what you may read here and elsewhere, color doesn’t tell you anything worth knowing (having said that, yours looks pretty dark).
The test strips are exactly what you need. They will tell you the ph of the coolants and you can learn where it needs to be for your self either from coolant manufacturers sites or The Petroleum Institute of America site (instead of relying on “experts” here or elsewhere (emphasis on the “” marks).
The Toyota Coolant is basically the same as other brands (it MAY have additional or different additives) and the strips work for it. The meters or bubble tester that just show glycol levels are not what you want, due to the fact that by the time the glycol levels have dropped the corrosion has gone to far. The strips test the ph levels which will indicate the corrosive effects of the coolant as it ages.

 

Based on your own posts not making anything up.

 

Take a look at the TSB and you will see it as you well know. Occurred in late 2019. Take another sip and calm down.

 

please link one, thanks

 

but i don't know, or i would have said so. please link the tsb

 

T-SB-0135-19

 

77K 2016 Prius and Headgasket Failure

 

Ok, thanks. I'm at the cottage right now so I'll check once I get back home on Sunday.

 

I tested the coolants for glycol and acidity. This is the result:



Top one is the engine and bottom one is the inverters. Glycol seem fine for both but acidity is just borderline. I guess I'll have to change the coolants before fall settles in.

 

It certainly wouldn’t hurt to change it this fall, or you could monitor it closely to see if it changes. If it was mine, I’d change it, especially considering the age (6 years).