Coolant change procedure?

Discussion on Air Conditioning/Heat & electronic controls for the same, radiators/fans/engine cooling and related items.
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Joined: Sat Feb 14, 2015 2:12 am
Location: SE PA

Coolant change procedure?

Post by xcidmigs » Fri Oct 07, 2016 12:05 am

With many of us having 2011 cars now well into their 5th year I find it strange no one has mentioned changing out the factory fill coolant? Is there any special to be aware of when doing it? has anyone used something other than dexcool? I'm well versed in the 90's hate threads about mixing dexcool and the infamous GM tablets that turned to mud etc. I think I'm going to do mine soon otherwise.

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Joined: Mon Jul 29, 2013 6:44 am
Location: Azusa,CA

Re: Coolant change procedure?

Post by smwalker » Fri Oct 07, 2016 2:03 am

I would be right there with you but the previous owner had everything done super early for some reason so I got a few more years. Service manual basically says to disconnect the radiator hoses, connect a flush gun and wash out the radiator. Disconnect the heater hoses and wash the core out with the flush gun at a lower PSI. Then with the engine isolated from both of the previous items hook up a flush gun and hose out the engine.

Here is a similar gun in operation: Flush Gun Video

That to me is a bit of overkill especially if your current coolant looks to still be in good shape and if you have lower mileage. I would just wait for a water pump failure or radiator failure to do the flushing gun stuff.

For normal maintenance I would just drain at the lower radiator, Refill with distilled, run to mix (few cycles of the engine fan), drain, refill with distilled, run to mix, drain a last time and fill with uncut dexcool. Option here could be to remove the thermostat to make the re-circulation faster but if you do that install a new thermostat and gasket.

Inspect the o-rings on the radiator cap. Replace if necessary.

Cooling system capacity is listed at 11.6 quarts so for 1 gallon of Dexcool into a cooling system with mostly distilled water left in it would give you about a 35/85 mixture. Dex-Cool is an ethylene glycol type of coolant. The main packagers of Dex-Cool specify no less than a 40/60 ratio of Dex-Cool/distilled, providing freeze point protection (FPP) to about -12ºF (-24.4ºC). All service manual says is to refill using 50/50 so 50% would be the target to shoot for.

That would mean after refilling and draining a few times what would be left in the engine would be mostly distilled water (maybe 90%??), lets just assume it is 100% distilled water left.

Adding 5 quarts of straight dexcool would get you a 43/57 mixture
Adding 6 quarts of straight dexcool would get you a 52/48 mixture

Depending on your location you can decide if you need the lower freezing point or the increased cooling capacity. In CA I would go for 5 quarts and fill my overflow with distilled.

More info here on ratios: ... d_146.html" onclick=";return false;

Also on the overflow bottle. Not to easy to remove and clean out as you have to go in through the fender liner. Could just use a siphon ball with a hose attached to remove the majority of the fluid.
Steve Walker
Azusa, CA
'11 PPV 9C3 Huron White

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