I have a 03 Boxster. It needs some anti-freeze, probably a half gallon (2 liters). I was told to use only the Porsche anti-freeze or the special kind just for Porsches (silicate free) that come in a small 1.5 liter bottle. I was reading the bottle for PEAK anti-freeze and it says "made for all model of all cars, no matter the color of the anti-freeze. Can be mixed with any antifreeze" It also says "silicate and phosphate free, safe for aluminum parts" the main quality of the Porsche brand. PEAK antifreeze is also ASTM-3306 certified, as is the Porsche brand.
Is it safe to use this antifreeze , mixed with the Porsche brand antifreeze? There is a MAJOR cost difference.
Thanks,
Jack

 

From everything I understand. Do not use any other antifreeze besides Porsche otherwise you could end up with a huge mess on your hands.

 

i use peak myself. everything that the porsche dealer has costs twice and three times as much, just cause it has the porsche logo on the bottle. if it has the same charecteristics as what porsche recommends, than go ahead. ive been using peak for two years now and everything seems to be fine.
if i were you i would drain the existing anti freeze and fill it all up with peak. that way you'll have new anti freeze and you wont be mixing brands

 

Damon,
Did you ever mix the two antifreezes? That's where I'm at right now. I need about another half gallon of antifreeze. It already is almost filled with fresh Porsche style antifreeze.
Thanks

 

I don't know how long you've owned the car, but I would take it in for a check up. The coolant is a sealed system and shouldn't be that low. You might have hairline cracks in the coolant reservoir (relatively common) that would need to be fixed prior to refilling and pressurizing your system again. I never experiment with fluids or systems that protect my vehicle.

 

i have never mixed two types of antifreeze, but as Pastorsteve told you, if you have that much coolant missing you could have a cracked coolant reservoir tank, exactly what i have at the moment. a hairline crack that u dont even see.
i would go to a specialist to check it out

 

You can also get the antifreeze from the VW/Audi dealer. They share the same specs as the antifreeze Porsche uses. I found the VW dealer usually the cheapest.