So a couple of years ago I bought 3 gallons of Zerex G05 & 3 gallons of distilled water ......mixed it all up and poured it all back into the 6 one gallon jugs. Also bought 2 one liter cans of Pentosin DOT4 brake fluid.
Took my 07 (Fred) in to a shop & had the coolant & brake fluid flushed/replaced. So today I took the remaining 3 gallons of 50/50 G05 & the other liter of DOT4 in to have the same done to my 08 (Wilma).

Owner's manual says 11.8 quarts coolant & 1/2 liter brake fluid. Last time no product was returned......assumed to completely replace the coolant they would need the entire 3 gallons of 50/50 mix + to totally flush the brake fluid they would need more than the 1/2 liter DOT4.

This time (same shop) when I got home I found they had returned to me a full gallon of my 50/50 coolant + about a half liter of the DOT4 brake fluid? I guess no way they completely replaced the full 11.8 quarts of coolant.......my fear is they diluted my 50/50 mix.......guess I'll wait till it cools down & check the freeze point/boiling point.......

 

So after the car cooled down, I opened the overflow reservoir. BLUE.....the G05 is GOLD ??????? The stuff in the reservoir tested 5 or 6 degrees warmer for a freezing point than the gallon of 50/50 G05 they returned to me. OK, I'm a dufus.......when this procedure is performed.....do they fill the radiator/engine from the reservoir or is there some other point like the old radiator caps cars used to have? If they filled through some other spot & failed to drain the overflow reservoir.....that would explain the blue still in the reservoir & them not using the full 11.8 quarts the manual calls for...?

In any case, I syphoned the 5 pints of blue out of the reservoir & replaced with an equal volume of the G05 50/50.

I'll wait a couple of weeks and let the expansion/contraction cycles mix the stuff in the reservoir with the stuff in the radiator/engine. If any substantial blue shows up.......I'll have to question everything they did?

 

I drained and flushed my car and it had the OEM blue coolant in it. The coolant that remained was pretty diluted. I added the G05 and I was surprised that the combination of fluids was blue. I actually calculated what the amount of the original fluid remained. That blue is pretty strong and overpowers the clearish golden coolant. Although the new blue is quite clear when compared to the solid blue of the OEM fluid.
No problem.

 

Good to hear, thanks!

 

In a post I did some time back and just after I did the change I said the color was green not blue. I have checked and it is green you can see the bottom of the overflow tank when you use a light.

The post was to see by calculation what the percentage of old coolant was using my method of draining.

 

It depends on whether they did a drain and refill of the radiator or performed a flush of the system.

There are two likely possibilities:

1. They simply drained the roughly 2 gallons of coolant that comes out when you open the radiator petcock and added back your 2 gallons of 50/50 premixed coolant. You should still have 50/50 mixure. You would also have approximately one gallon of older coolant that is still in the system because the engine block was not flushed or drained. The fluids are compatible and the resultant color would be blue once mixed.

2. They drained the radiator and then continued by flushing the system, to include the engine, with water. The coolant that was in the engine is now replaced with water. They added your two gallons of 50/50 mix to refill the coolant system. You now have roughly a 33/67 mixture of coolant/water.

The correct premix ratio when flushing the system is 75/25 coolant/water unless the engine block is also drained.

 

With my device it was reading between minus 30 & minus 34. I then removed about 5 pints from the reservoir & replaced that volume with an equal volume......now reads after circulation....minus 37 F. Still have a little over a half gallon. After I run it some more with the heater on....I'll replace what's in the reservoir again. At least most of what's in the system is new with good anti-corrosion properties. Everything in the system is crystal clear.....just tinted a little blue. Kind of irritating.....suppose I should have been clear with the shop that I wanted EVERYTHING flushed and replaced. Compared with prices at the dealership over the years this shop has saved me thousands of $.

 

Good or bad most shops rely on the customer being ignorant on matters relating to their car.