[gde061]

I succeeded in pulling the pesky coolant quick-connect hose without resorting to the cutter. But now I want to be careful about what I use to flush out any oils that got into the cooling loop from the leaking OFHG.

If I remember how I learned years and years ago, my dad used water + washing soda or it might have been white vinegar first, then the washing soda... something like that... before putting in the "expensive" coolant. Now the coolant is GOURMET and the coolant loop full of stuff that hadn't been invented yet back then, so I'm hoping for some modern application specific degreaser advice. This thorough post on flushing techniques suggests using something called L-11... not available locally, so I have to order it from his site apparently.

I've seen other "flush and cleaner" products (Prestone, Blue Devil, etc.) locally on the shelves. However BMW seems to be finicky about what brand of stuff goes into the coolant loop... with a cooling loop full of sensors, plastics, o-rings, and such. Using the fancy pressurized tool to siphon out residual oily gunk via. the expansion tank is not an option for me -- seems like that might be BMW's official solution. So what is the best but also economical and safe flush compound to use?

[Efthreeoh]

Laundry detergent. Detergent contains surfactants, which break the surface tension of the water molecules and allow the oil to become soluble and carried away by the water. Do not use a soap, all that will do is foam up.

[6Inarowmakesitgo!]

Originally Posted by Efthreeoh

Laundry detergent. Detergent contains surfactants, which break the surface tension of the water molecules and allow the oil to become soluble and carried away by the water. Do not use a soap, all that will do is foam up.

I use Dawn dish detergent. Works great. You only need a SMALL amount.

Have used a regular hand soap and combined with an overheating issue, this old POS Chevrolet would shoot bubbles from the expansion tank.