interested in opinions - dexcool to g05

[STL_G8GT]

Team BITOG,

I swapped our 99 suburban over to G05 from whatever universal green the last owner was using in it.

At the same location of the suburban is a 2009 Pontiac G8 GT (aluminum block, aluminum heads). The car sits for 8 months out of the year, and it was time for a coolant swap. It had dexcool in it.

Wanting to simplify my on hand, so I did the research and decided to switch over to G05 for the Pontiac as well. Everything I read was that the coolants are not generally compatible as a top up, but perfectly fine after a flush.

The coolant system capacity is just over 11 quarts, and draining from the radiator clears about 4.25 quarts. Here is the flush sequence I used.

Seven times I dumped the rad, and added distilled water. (Brought the car up to temp with the thermostat open each time.). The eighth time I added 50/50 go5/distilled. The ninth time I added concentrated g05. In total I ran 9 gallons of distilled and 1.5gallons of g05 through the car.

I ran it through AI because Half-Life calculations are beyond me, and it came back with this:

After the 9th fill, I am left with .1357 qts of dex cool mix from the original system fill, that is 1.2% of the total capacity. Also, I'm about dead on for a 50/50 mix G05/water.

Because for whatever reason I'm OCD, I'm considering a couple more drains and filling with 50/50 GO5 mix each time.

I've seen stuff where people talk about manufacturers recommending less than 10% concentration before mixing coolants. In personal experience out there am I well past the threshold of danger here? The only reason that I am particularly nitpicky on this is that I've taken really good care of this car, it's a low mile survivor, but it does sit for 8 months, I don't want to come back to a disaster next fall...

 

[ArrestMeRedZ]

I converted my '97 C2500 5.7 Vortec from Dexcool to G05. I used the Prestone radiator flush kit that installs a garden hose attachment to the (I think I remember correctly) heater hose line and throughly flushed the system with tap water. Then did a couple of drain and fills with distilled water. On the last fill, I drained the radiator then filled with concentrated G05. By my calculations using system capacity, the amount added brought it up to very close to 50%.
Your way takes a lot longer and uses more product, but it achieves effectively the same result. I don't believe for a second that amount of Dexcool left in the system will affect anything.

 

[thastinger]

IDT you could do much better than you have.

 

[JHZR2]

Team BITOG,

I swapped our 99 suburban over to G05 from whatever universal green the last owner was using in it.

At the same location of the suburban is a 2009 Pontiac G8 GT (aluminum block, aluminum heads). The car sits for 8 months out of the year, and it was time for a coolant swap. It had dexcool in it.

Wanting to simplify my on hand, so I did the research and decided to switch over to G05 for the Pontiac as well. Everything I read was that the coolants are not generally compatible as a top up, but perfectly fine after a flush.

The coolant system capacity is just over 11 quarts, and draining from the radiator clears about 4.25 quarts. Here is the flush sequence I used.

Seven times I dumped the rad, and added distilled water. (Brought the car up to temp with the thermostat open each time.). The eighth time I added 50/50 go5/distilled. The ninth time I added concentrated g05. In total I ran 9 gallons of distilled and 1.5gallons of g05 through the car.

I ran it through AI because Half-Life calculations are beyond me, and it came back with this:

After the 9th fill, I am left with .1357 qts of dex cool mix from the original system fill, that is 1.2% of the total capacity. Also, I'm about dead on for a 50/50 mix G05/water.

Because for whatever reason I'm OCD, I'm considering a couple more drains and filling with 50/50 GO5 mix each time.

I've seen stuff where people talk about manufacturers recommending less than 10% concentration before mixing coolants. In personal experience out there am I well past the threshold of danger here? The only reason that I am particularly nitpicky on this is that I've taken really good care of this car, it's a low mile survivor, but it does sit for 8 months, I don't want to come back to a disaster next fall...

Does the engine have a block drain? That would make things easier and more definite.

 

[Cressida]

OP - we get the OCD around here, many of us suffer from the same...

I think you have it nailed so you can move on to your next project. I switched two of our older GM vehicles over to the same G05 15 years ago and they both continue to operate fine today, with clean cooling systems and on original radiator hoses. I probably did about 4 drain and refills with a garden hose and then one or two with distilled water and then the final 50/50 mix. Of course I have done another drain and refill about every 5 years or when a water pump was replaced after leaking.

One thing I note and appreciate about Zerex is they list the finer details of the ASTM test results for their coolant products so they are my go to brand. The G05 shows excellent results in those test too.

 

[STL_G8GT]

Does the engine have a block drain? That would make things easier and more definite.

Yes, it does, there's a drain on the left hand side that's not too difficult to get to, the block on the right though you have to remove the starter to get to it. That was kind of my reasoning behind doing the slower 4 quarts at a time process. I just hate dumping coolant all over everything when you pull block drains that don't have nipples on them.

 

[JHZR2]

Yes, it does, there's a drain on the left hand side that's not too difficult to get to, the block on the right though you have to remove the starter to get to it. That was kind of my reasoning behind doing the slower 4 quarts at a time process. I just hate dumping coolant all over everything when you pull block drains that don't have nipples on them.

That’s fair, my older MB engines have a bolt, and it’s a mess, the later (still old) ones have a nipple and it’s so clean and painless.

What I’d do is just run it a bit and then do 1-2 more radiator drops. Indeed you have very little in there, but you’re changing chemistry, so what’s bound to surfaces will change, some chemistry will be depleted from the g-05. Replenishing a bit gets more dilution and an update on the inhibitors and silicates.

 

[STL_G8GT]

I converted my '97 C2500 5.7 Vortec from Dexcool to G05. I used the Prestone radiator flush kit that installs a garden hose attachment to the (I think I remember correctly) heater hose line and throughly flushed the system with tap water. Then did a couple of drain and fills with distilled water. On the last fill, I drained the radiator then filled with concentrated G05. By my calculations using system capacity, the amount added brought it up to very close to 50%.
Your way takes a lot longer and uses more product, but it achieves effectively the same result. I don't believe for a second that amount of Dexcool left in the system will affect anything.

I really appreciate it, I won't worry about it in the short-term then and probably before we leave I will just do one of the drains and replace with 50/50 because why not

IDT you could do much better than you have.

Thank you, puts me at ease

OP - we get the OCD around here, many of us suffer from the same...

I think you have it nailed so you can move on to your next project. I switched two of our older GM vehicles over to the same G05 15 years ago and they both continue to operate fine today, with clean cooling systems and on original radiator hoses. I probably did about 4 drain and refills with a garden hose and then one or two with distilled water and then the final 50/50 mix. Of course I have done another drain and refill about every 5 years or when a water pump was replaced after leaking.

One thing I note and appreciate about Zerex is they list the finer details of the ASTM test results for their coolant products so they are my go to brand. The G05 shows excellent results in those test too.

Yeah, I could have gone the garden hose route, but I didn't, the easier route in this case of course ended up taking more time, haha

 

[STL_G8GT]

That’s fair, my older MB engines have a bolt, and it’s a mess, the later (still old) ones have a nipple and it’s so clean and painless.

What I’d do is just run it a bit and then do 1-2 more radiator drops. Indeed you have very little in there, but you’re changing chemistry, so what’s bound to surfaces will change, some chemistry will be depleted from the g-05. Replenishing a bit gets more dilution and an update on the inhibitors and silicates.

Yes, I think that's the plan, I will wait a couple drives and then do another drain and be confident that I'm in a good spot.