AC guys, I have a question.

[nthach]

I was under the understanding POE and PAG oils were miscible but I read a few posts on other forums that it’s not advised. I’m debating picking up a UView Spotgun Jr. or Eco-Twist kit to add a little oil and UV dye to a friend’s Subaru. The one I’m looking at has POE oil for hybrid/electric compressors, like the one used on a Prius. Those compressors require a ester oil with high dielectric strength - else any electrical “leakage” is enough to throw the CEL, log chassis codes for high-voltage leakage and disable the HVAC system. I would like to keep one injector around.

So, can I mix POE oil with PAG oil or no?

 

[ZeeOSix]

Looks like the answer is yes.

https://fjcinc.com/understanding-the-differences-between-a-c-compressor-oils/#:~:text=Because%20mineral%20oil%20and%20PAG,%2D12%20and%20R%2D134a.

 

[Kurtatron]

I always heard ester oil is compatible with both mineral oil and PAG but PAG and mineral oil are not mixable. Mineral oil was used in the older r-12 AC

 

[Chris142]

I was taught in ac class to add a small amount of ester to every ac job. The ester will lubricate where PAG won't and will soften seals possibly stopping small leaks.

Seems to have worked for me for the last 20 years.