Took my car in for a coolant leak, and it turns out it was leaking from the thermostat bypass plug. That was fixed, but they topped the coolant off with Peak. I questioned that on the receipt and was told "we've been using that for years, it's fine."

I looked at the expansion tank when I got it home and it's still bright pink like G12 should be, so I guess percentage-wise, it must still be *mostly* G12, but I'm worried. Should I flush the system and replace with new G12 at the first opportunity, or will it likely be OK?

Either way, I'm unlikely to take the car back to the particular shop I got this done at, because I feel like they should know that that's not what's recommended for these cars. I guess I'll go back to the guy I like and trust more, even though he's a much farther drive for me.

Just makes me wish even more than usual that I had a proper garage with a proper set of tools so as to be able to tackle at least some of these jobs myself.

 

i would at least take it back and tell them what audi recommends and say you are worried that problems might arrise down the road. at least make them flush all the g12 out and then put the new coolant in. I know its not recommended to mix coolants on our cars. I know my tech wont use anything other then what audi recommends Period.

 

Peak is a universal coolant, it CAN mix with G-12 better than other coolants but it still coagulates over time. I personally don't like it because peak is still ethylene based glycol, it tends to eat away at our OEM seals.

 

I was hoping to see a reply from you, auditech79. Thanks for the info. I'm *guessing* that I've got a pretty small percentage of Peak in there, as I hadn't lost very much coolant when I brought it in for repair; it was only a little below the min line on the expansion tank, and they filled it to the max line. Given that, do you think it'd be ok to run it for a few thousand miles and just get it flushed and refilled with G12 at my next service? (I'm about 4K miles away from my 90K service now.)

 

Yeah thats around a 90% dillution, it should be fine.

 

Thanks for setting my mind at ease. I appreciate the time and expertise you contribute to all of us here.