GlenL

You boys are silly. There are reasons people go on my ignore list. One is that I read this at the office.

Any coolant that says "phosphate and silicate free" will be fine. That's almost all anti-freeze you find these days except for the cheapest store brands. Distilled water is good. What's better is actually servicing it periodically. Drain and fill every three years. Or four.

You can go ahead and hunt down fancy brands and dealer-only mixes if you want. Change it on schedule and you'll never know the difference.

One final note: Havoline Dexcool was reformulated and was never a problem for 928 engines in the first place. I could re-research that...but I'm bushed.

Phosphate and silicate free and change it.

tveltman

If you are obsessive, check out

http://www.riccachemical.com/catalog...px?qs=R9150000

The 9150 is the stuff I use in lab. It's the purest water you will ever find. From Arlington, TX too, so yay for american industry

Pcplod

I was told once (by a pretty reliable source) that all the antifreeze in the world was made in two (or was it three) places, and then sold to all the different "manufacturers" for packaging in their assorted containers. Does any one know if this is true, or possibly, if it used to be the case but has changed now??

If this is true (like GlenL says) you just need to look for the antifreeze with the right contents and you are good.

dr bob

FWIW, silicates and phosphates in coolant do play important roles. The obsession with 'phosphate-free' and 'silicate-free' are due to histories from engines that don't have the coolant changed regularly enough. Car manufacturers are on a bent to avoid having to do coolant services while their 'full maintenance contract' cars are still within warranty. So we have extended-life coolants with new chemistry that's there just for the sake of the extended life label.

For the frequency of 928 coolant changes I do (generally about 12-18 month intervals) it's no stretch getting the G-05 from across town. At the same time, almost any modern coolant would work in its place ---if all the old coolant is completely flushed out first---. It's too easy to get the right stuff, but it's not like those "other" products will instantly cause catastrophic failure. In the end, the best coolant is probably the one you replace every year.

mx22

Thanks a lot guys. I guess Zerex is pretty much what everyone here uses, so I'll need to find if any of the local stores have it.

My car has green coolant right now. I guess I will need to drain and then flush the system. How do you flush it though? Drain coolant, put plugs back in, fill the car with distilled water and then drain it?

Thanks!

danglerb

Amazon.com has Zerex G-05 undilluted for about $13 with free shipping ($25+), in Socal Graingers apparently has it for a bit less, but can be a pain for a non business to buy from.

Colorful chart of 4mb and two pages that says pre 95 Porsche uses G05
http://www.valvoline.com/pdf/Zerex_CoolantChart.pdf

Pentosin I think makes the Audi coolant, the G12 anyway.

Charley B

Is it just me, or does it look like they have traded heads?

danglerb

http://www.pentosin.net/f_antifreeze.asp

Says the Porsche 928 should use Pentofrost NF, which is blue green.

Mark SF

The green stuff only lasts 2 years so changing it every 18 months is not a bad idea. Zerex G-05 is long life, 5 years, so changing it every year is a complete waste. Pick you own interval, maybe 2-3 years?

Mark SF

In the past I've found you can't beat back-flushing with a hosepipe.

1) Pull the top and bottom radiator hoses, put hosepipe in radiator bottom hose (so flow is in the opposite direction to normal) and run until all the silt comes out.

2) Engine is trickier to do - you could use the heater outlet pipe from the block, or remove the thermostat and put the hose in the top hose.

Some systems are full of rust and crap while others are clean. My 20 year old XJS was clean as a whistle.

Also the radiator always seems to be worse - guess that's where the crap accumulates.

So I would suggest back-flushing the radiator and if it seems pretty clean go ahead with the fill with distilled water.

NB The G-05 is intended to be compatible with older coolants so you don't have to worry about getting the last drop of the old stuff out.

hacker-pschorr

That's good to hear since I used Zerex G-05 (the Mercedes labeled stuff) in my fathers 355GTS. The engine comes out every five years for timing belt / water pump job.

Landseer

Big shopvac