-7F protection with mix of Propylene/Ethylene

[oilboy123]

I replaced the thermostat in my Dads Dodge Caravan. I put in about 65% Amsoil propylene antifreeze.
The water pump went bad later and the shop changed over to the green antifreeze. They wrote down that they installed 2 gallons. The system is 13.4 qts. I am suspicious of how much they installed now.

I tested the antifreeze with a ethylene glycol tester that showed -7 protection.
The problem is I now have a mix of Propylene and Ethylene. This brings up the question? Amsoil says it's antifreeze is compatible with other antifreeze formulations. But if the two mix what do you tester do you test it with? This is something I never thought of before?

I assume the shop drained the antifreeze by pulling the water pump off and maybe a gallon of the Amsoil stuff was still in the system, If that. I think I will let it go for a while then I need to changed the hoses and will then switch it back over to Amsoil again. I did not have time to change the hoses and will do that as well.

I don't feel comfortable running a -7 formlation for corrosion protection.

 

[paul_e320]

Those ethylene glycol testers (ball or float type) are only accurate to about +/- 8 deg F, at best. A refractometer is the proper tool to use as these have +/- 2 deg accuracy or better. The refractive indicies of propylene vs ethylene are fairly close, so for what you're trying to test should be OK and hopefully give you +/- 5 deg accuracy.

Regards,
paul...

 

[oilboy123]

I would like to get one.

I am doing some work to the vehicle and will be switching the antifreeze to Amsoil propylene glycol.