Grease in Radiator - Detergent or Vinegar? I think I know.

[Hoogah]

I need to clean my cooling system of grease that's got in via the water pump. I've checked out the relevant threads here and also consulted my local radiator repair man. However, this revealed recommendations for both dishwasher detergent and vinegar, but no consensus as to which is better. I wondered if the vinegar recommendation is really meant to be for rust gunk ONLY, and some people just assume that it's also good for grease?

Anyway, I hate getting conflicting advice, so I decided to do my own test to see which is better at dissolving grease.
I added a teaspoon (4 g) of grease to 250 ml of each of the following treatments:
1. COLD water + 1/2 tablet of dishwasher detergent
2. HOT water + 1/2 tablet of dishwasher detergent
3. COLD 50/50 vinegar/water mix
4. HOT 50/50 vinegar/water mix

The HOT treatments used hot water tap temperatures only.
I shook each jar vigorously for 3 x 1 minute each over the next 15 minutes and set them aside.

The photos show the results with a view from the side and also looking down into the jars after 20 minutes.

The dishwasher detergent has done a great job of dispersing the grease and holding it in suspension, such that I would be pretty confident that it would drain effectively from the radiator. Water temp didn't seem to make any difference to the result.
The COLD vinegar/water mixture appears to have done nothing at all.
The HOT vinegar/water mixture has completely broken the dollop of grease up but it is not held in suspension. It now coats the inside of the jar. I would not like this to be the result in my radiator and engine.

I'm glad I did this, as it is clear to me now that vinegar is NOT an effective solvent for grease in this test. I'm going with the dishwasher detergent!

I'm sharing this in case anyone else has been wondering the same thing.