Possible problem with Subaru Coolant Conditioner

We have seen a rash of 00-02 Legacy's recently with overheating problems, esp. with the AC on. They all have two things in common:

1) They all have blocked radiators (some have temperature differences of up to 30 degrees from one side to the other)

2) They all rececently had the Subaru Cooling Conditioner WWP-99 Service Campaign performed.



For those that don't know: Subaru acknowledged a problem with the headgaskets on certain 99-02 MY 2.5L Phase II engines and decided to try to correct the problem by having us dealers add a "special" Coolant Conditioner (aka headgasket in a bottle) to correct it. So far, it seems to be working. The number of headgasket jobs we do each week has dropped to almost "0" for these engines. However, these recent events have us all wondering if the conditioner does more harm than good in the long run.

That being said, I should clarify that I AM NOT SAYING THAT THE CONDITIONER IS TO BLAME. At this point it looks like a bad coincidence. It could be that these Legacys got a bad batch of radiators. It could be that the owners of these cars added something to their cooling system on their own. We don't know yet and we have not heard anything from Subaru regarding other dealers reporting overheat conditions on cars affected by the campaign.

If you own a Subaru that has had this campaign completed, keep an eye on your temp gauge. Again, I am not saying that the conditioner is to blame, but it does seem suspicious. Please don't misuse this information to throw a fit at your local dealer. This is all speculation at this point.


Dave