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Zerex G-05 coolant has been recommended many times here, as being a good choice for our engines and readily available. I have been using it for years. Consider this a PSA if you wish, but I am done with that crap.
When GB took apart our 240K-mile GT engine a few years back for rebuild, there was significant corrosion on the heads which required welding. "Dumb coolant choice by the various PO's", said I. We stuck with G-05 for the newly build engine, at my foolish request.
Now fast forward three years and 40K miles, the engine is apart for reasons unrelated to coolant but it was a chance to check everything. So how did our favorite G-05 coolant do? Pretty freaking crappy, in my opinion-- corrosion in four different spots, similar to the pic below. Only a few thousandths deep (maybe 0.004" max) but corrosion none the less, and right up against the fire-ring. And no, not in the areas that were previously welded. And no, it was not mixed with tap water.
No previous unknown coolant, no unknown history, no excuses. Just a bad choice. I am done with that crap, heads are getting shaved and Porsche 000-043-305-75 is going in. Worrying about saving $50 for a coolant change is absurd. [\rant]
Bummer Jim. But thanks for sharing. I agree, if the Porsche juice is better stuff then $50 is great insurance. However how can one be sure the Porsche branded stuff is legit? I assume Greg has some emperical evidence to that end?
TL;DR: Prestone Longlife Coolant. Comes in the yellow plastic jugs at Walmat.
After seeing these heads that just freakin' marinated in that coolant for 14 years, it's going to be very hard to convince me that it is a worse choice than whatever is in Porsche's black jugs. That - the Porsche - stuff's ingredients are, as far as I'm concerned, dictated by accountants and environmentalists. When the coolant's recommended change schedule is 'never' or 'when system opened' it gets a big pass from me.
I am done with that crap, heads are getting shaved and Porsche 000-043-305-75 is going in. Worrying about saving $50 for a coolant change is absurd. [\rant]
TL;DR - Different coolants for different MY ranges of Porsches. Based upon a day (take that for what it's worth) of researching, what goes into coolant (base chem and additive packages) is dependent upon a lot of factors including things like water pump seal materials, block and head alloys, environmental concerns, etc. In other words, I left my research not convinced that Porsche's newest coolant was the best choice for our 30-year old 928s. Then, a couple of months later, I pulled the heads that are the subject of 'my' thread.
My 81 was the "victim" of having coolant changes done with mostly distilled water.
When I pulled the heads and dropped them off Greg's machinist told me they were some of the best heads from a 928 he had ever seen corrosion wise.
Keep in mind this car basically sat for 11 years with just water in it. It had some mineral deposits but they got flushed out like a water heater.
But it never really gets freezing cold here in SoCal so we can get away with this. I run 25% or less of anti freeze and it seems to do well.
I'll probably add in Porsche coolant next time because it should be good for 10 years, or so they say.
The price difference is like half a tank of gas so it really isn't worth cheaping out on considering the cost of repairing corrosion as you've stated above.
I've been using Zerex G-05 but since I haven't removed the heads I have no idea what's going on in there.
It's funny, Advance Auto lists this Pentofrost NF in stock, but claims it doesn't "fit" my car...they recommend Prestone Extended Life for some reason, not that they would know.
I had changed all my cars over to G05 and Sean and I were talking about antifreeze on the phone just yesterday. Looks like I'll be changing all to G13?
I just put G05 in 3 years ago. That's it, I'm buying Mercedes blue antifreeze from the dealer. These new MB engines are all aluminum and I highly doubt the blue coolant is corrosive. It's also cheaper than Porsche's recipe.
I believe the Mercedes coolant is equivalent to G48 and is only $18 a gallon. It also uses the same HOAT compound as the OE Porsche formula if I'm not mistaken.
TL;DR: Prestone Longlife Coolant. Comes in the yellow plastic jugs at Walmat.
After seeing these heads that just freakin' marinated in that coolant for 14 years, it's going to be very hard to convince me that it is a worse choice than whatever is in Porsche's black jugs. That - the Porsche - stuff's ingredients are, as far as I'm concerned, dictated by accountants and environmentalists. When the coolant's recommended change schedule is 'never' or 'when system opened' it gets a big pass from me.
YHMV (Your heads may vary.)
It also begs the question, how can any of us be sure that any brand of coolant hasn't changed their formulation without changing the branding on the container? I assume that there are no regulations preventing coolant companies from changing their recipe (maybe or maybe not to the detriment of our old cars) without changing the container. Sure the list of active ingredients will likely be revised but unless you are a coolant scientist the rest of us would be oblivious, right?
10-23-2019, 11:25 PM
Done with G-05 Coolant ... Completely, forever.
