Well my 80TD just starting getting a little hotter than usual (maybe 90 celsius) today while doing a lot of around town stuff. Normally I just cruise it to and from work so never noticed it get hot. Also my heater does not work. I know the W123 has the fabled ACC system known for failing, but I heard that an improperly functioning thermostat can be a cause for the heater not working. I figured I might as well replace the thermostat and hopefully kill two birds with one stone.

Grabbed a new 80 degree tstat from Napa Auto and a bottle of Sierra, which was the only brand they carried that was made with Polypropelene Glycol. It was because of this discussion that I decided Sierra might work out just fine.

I remember I had a similar decision to make when I changed the coolant in my 87 Syncro Vanagon, as their was people who only suggested that you use VW certified coolant and those that said coolant made with Polypropelene Glycol would be fine. I opted for Sierra back then and here I am doing it again.

Maybe it's because I don't plan ahead and always change my coolant on a Sunday, or maybe it's because I trust that Sierra is a good brand, either way though I'm glad this discussion is going on.

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon