Coolant alternative/upgrade to save $$$...

[BrandC]

Okay all, I've been doing some homework. I have some generic green coolant in my M42 and I don't want it there anymore. I am going to flush it completely.

The BMW coolant we use in our E30's from the dealer is equivalent to VW's G11 (Blue coolant), which is phosphate free. Since the switch to OBD2, many manufacturers have switched to a phosphate AND silicate free coolant. This is G12 for VW's.

I upgraded to a cheap off the shelf alternative to G12 called "Prestone Dex-Cool" in my '95 GTI VR6. It's about $10 a bottle at Autozone. I'm pretty sure I can do the same for the M42 since BMW coolant is equivalent and it is much cheaper and less likely to clog/gunk up our coolant system.

My question is what are some ways to completely FLUSH (not bleed) all the green generic coolant in my M42? I want to flush every last drop of coolant out in my M42. I read a VW TSB that said upgrading to G12 from G11 meant completely flushing the system before b/c G11/G12 mixing makes a gunky mixture.

So here's what I'm thinking:

1. Drain as much coolant as possible
2. Fill the cooling system with distilled water and a radiator flush, bleed, drive around for 1-2 days.
3. Fill with distilled water/Dex-cool mixture.

or

1. Drive the car around at operating temperature.
2. Wait so the engine is not burning hot, drain the coolant while the thermostat remains open. (leave drain plug open too)
3. Take a garden hose and fill it with water and let the water flush out any remaining coolant.

Let me hear what you guys think. TIA.

[NC325iC]

i would say the first one but lose the distilled water and just use plain ass water
and add in another step btw 2 and three where you just use water and drain, might have to do it a couple times to be sure its all out

[AndrewBird]

^^^ What he said. Just use regular water and I would just fill and refill it a couple of times until all you get is clear water. And you don't need to drive the car, just let it idle until it warms up fully. You can use a piece of cardboard or something to block airflow to the engine to help it warm up also.

[AlarmedBread]

I would NOT leave a radiator flush product in the car for several hours, much less several days. Get it out of there as quickly as possible or don't use it at all unless you have rust etc. in your cooling system.

A little tide laundry detergent (mix it up in a bottle of water first...) run that then flush it out with the hose does wonders to clean out anything, even oil. You don't want to know how I know. :-(

Dexcool is bad, m'kay.

EG for life.

[mmmjboner]

i would say the first one but lose the distilled water and just use plain ass water

i personally would use distilled water, just to be safe that the tap water i would otherwise use does not contain minerals that would contaminate the new coolant.

Q. How do I flush my cooling system and install a fresh fill?
A. Using a chemical flush prior to the fresh fill of antifreeze/coolant is an effective way to remove deposits from the cooling system. Prestone® offers several flushes that are designed for everything from routine maintenance to lime or rust scale. All of these cleaners are compatible with the cooling system components of any vehicle. We recommend the following: Use Prestone® Super Flush for routine maintenance. Use Prestone® Super Radiator Cleaner to remove corrosion and lime scale. If the directions on each of these cleaners are followed correctly, the end result will be an empty radiator and mostly water in the engine block and heater core. At this point, use a mix of 50% to 70% Prestone® Antifreeze/Coolant and water. This is easily accomplished if you know the capacity of the cooling system. Example: If the owners manual of your vehicle indicates that the capacity of the cooling system is 8 quarts, then you need to install 4 quarts of pure antifreeze. Note: Once the desired amount of concentrated antifreeze/coolant has been installed, the cooling system must be topped off with water to ensure a complete fill. Prestone® products also offers a Flush N' Fill Kit for backflushing the cooling system. This kit fits some cars and most light trucks. This backflush will remove more deposits than the chemical cleaner alone. If you are able to access the inlet heater hose on your vehicle, we recommend that you use one of the cleaners and then backflush the system.

http://www.prestone.com/carcare/faq.php

[StereoInstaller1]

Here is my tried and true (but somewhat dangerous) method of cooling system flushing:
1. Remove thermostat
2. Check and make certain heater is set to hot.
3. Remove upper radiator hose from engine.
4. Wrap shop rag around water hose TIGHTLY, then stuff into radiator hose.
5. Stuff air nozzle into same coolant hose
6. Crank on the water, and blast with air from nozzle. I do the air in pulses, seems to clean better and cause less damage.

You will be amazed at what comes out of your coolant system.

Of course, you will want to drain the system completely before refilling.

Luke

[BrandC]

I used to work in a repair shop and I was taught to use distilled water to avoid any contaminants from breaking down the rust inhibitors in coolant.

Dex-cool only breaks down when it is mixed with other types of coolant. I guess I just need to figure out a way to completely flush the system.

As far as radiator flushes go, it's not a necessary step. I have used it before with success and not harming the cooling system parts/gaskets. I will only leave it in there for a few hours tops.

StereoInstaller: I do not have access to compressed air, so would just using the pressure of a garden hose suffice?

So nobody has had success with switching coolants? Lots of ppl swear by Dex-cool and other phosphate/silicate free type coolants. I guess I will just have to try it on my own.

Any other recommendations for completely flushing the cooling system?

[FredK]

Dexcool is bad, m'kay.

EG for life.

Dexcool IS ethylene glycol (EG)!

All coolants use ethylene glycol (except the pet-safe ones, which are propylene glycol (PG)).

The difference between coolants is not the EG they contain, but the corrosion inhibiting package.

Dexcool uses organic acids (OAT). Most conventional coolants use inorganic compounds to prevent corrosion (IAT). The last major type of coolant additives are the ones that use hybrid organic acid technology (HOAT). These are the ones you see advertised as "add to any type of coolant system." HOAT coolants do not suffer sludging problems or corrosion problems like OAT (Dexcool) coolants.

OAT and HOAT coolants last around five years, and conventional coolants last around two. However, it's cheap insurance to flush and fill every two years no matter what formulation you have.

BMW uses Zerex G-048, a HOAT coolant. The closest equivalent is Zerex G-05, which is available at your local Auto Zone for around $11 a gallon. I use G-05 exclusively. I switched from green coolant and have had no problems to date.

[Garageaholic]

I used dex-cool and it ate out my coolant pump seal and needed a new pump.

Use prestone (the green stuff) and mix it 50/50. Don't try saving a buck or some time. DO IT RIGHT. if you have any respect for your car, you'll do it the right way.

I would flush my coolant system by removing the block coolant plug and point a hose in the coolant overflow. Turn the engine on. That ensure that their is liquid circulating, and that you have constant water going through the engine. It will flush it out and just exit at the hole in the block.

[RobertK]

I use the new Preston 50/50 yellow mix (HOAT) safe for aluminum cooling systems.

I've always been told to avoid DexCool antifreeze because it has a tendency to eat gaskets away. This happened to a close friend of my on his Chevy Tahoe which calls for the use of DexCool. It ended up really screwing up his engine somehow. He told me the mechanic that fixed his Tahoe told him not to use DexCool even though GM recommends it because of all the problems he's seen it cause on other cars. (Mainly gasket failure)

[BrandC]

Ok so it looks like Dex-cool is more questionable in reputation than I had thought.

I guess anything that is safe for aluminum parts and is phosphate free should be fine. I just didn't want to use BMW coolant b/c I know lots of us do mods that require us to drain the coolant first and it gets expensive to fill with BMW coolant.

M3fan4eva: BTW, I have an M42 but I'm pretty sure there is a passage on the block as well.

[AdamF 88iS]

The engine doesn't have to be hot at all to get all the water out. The radiator will drain from one side of the thermostat, and the block drain will get everything out from the other side. I have my doubts if dumping a bunch of cold water into the motor when it's hot is a real good idea for your aluminum head.

BMW coolant is set up to lubricate the water pump properly, keep all the seals in their right places, and prevent corrosion on the the aluminum. I'd use it or something very close to it.