So, I figured out that my oil cooler is leaking internally. Oil entered coolant. I have a thread on this.
Before I install new oil cooler I am trying to flush out coolant system as best as possible.

What I have done so far......

1. Drained coolant via radiator petcock (all drains have been through here).
2. Added tap water, ran engine to operating temp. Drained.
3. Changed motor oil and filter. No signs of coolant.
4. Added Motorcraft VC-1 flush and ran engine to operating temp. Drained
5. Repeat #2.
6. Repeat #2.
7. Repeat #4
8. Repeat #2.
9. Installed new coolant reservoir (degas bottle).
10. Repeat #2.

At this point I still have film of oil left behind (beige scum line) in the clear container where I drain water into each time. I clean scum line after each drain to see how much scum/oil is coming out each time (scum line every time). It is getting a little less each time, but I feel it will be there even after 20 drains.
My new reservoir has some of the scum film in it as well. I removed and tried to clean with hot water and dawn dish soap but some of it still remains.

Is the remaining oil residue depositing itself and staying in the radiator? Heater core?

What next steps can I try to remove all oil residue or is it just not feasible?

At this point, unless there is more I can do, I am considering installing oil cooler, do one last water flush (Step #2), add 3.5 gallons of concentrated coolant and fill the rest with distilled water, and drive. Approx. 3 gallons is drained with approx. 4 gallons remaining in engine. Since the total coolant capacity is approx. 7 gallons, if I put in 3.5 gallons of concentrated coolant and fill with water, I should reach 50/50. Sound correct?


After a few thousand miles, I can do another chemical flush, drain, water flush, and add new coolant, new radiator and new thermostat. Thoughts?

Thanks!

 

When I do flushes at work for oil cooler failures, granted on diesels, I remove the thermostat from the housing, reinstall with the o-ring in place to seal and then I fill the system with water and simple green. Drive it for about 10-15 miles or let run for about an hour then drain. I do this a few times which usually gets most of the crud out, then I pull the block drains from the engine, stick a hose in the upper rad hose and let it flush the block out for awhile. I repeat this process until I get no more oil in the coolant. Then I replace the leaking cooler and repeat the flush process one more time to ensure all the oil is removed from the system. It takes time, but it works. You need something that will lift the oil off the surfaces inside the cooling system which simple green is very good at.

 

One block drain is not easily accessible (behind a motor mount). The other one has a soft metal head, is shallow, and is easily stripped. I don't want to strip it out trying to get it out. Is the block drain removal a must?

I've heard of dishwasher soap (low suds) but not simple green. Does it produce much suds?
Apparently, the Motorcraft Premium Coolant Flush didn't do much for the oil removal.

How much simple green is used for a 28qt cooling system? I imagine there was close to two quarts in coolant, based on how much oil I measured when I pulled dipstick. It was at lower mark.

 

Wouldn't say its a must but it does help. If you cant get it out, don't worry about it. It will probably take some more flushes to get all the simple green out is all. What I would do without pulling block drains is pull the radiator petcock out and let the water hose run though the coolant bottle for a little while, starting the truck every few minutes and let it run for a minute or 2 with the hose still running water through. This will circulate the hose water through the block. Simple green has some suds, but not a lot.

 

Is this simple green you are referring to:

https://simplegreen.com/products/pro...ner-degreaser/

How to Clean a radiator:

https://simplegreen.com/cleaning-tip...tive/radiator/
​​​​​​

 

Should I combine your first post method with this second one....minus the block drain removal and water in upper radiator hose?
I'll have to let it run rather than drive as it's up on stands and coolant hoses to oil cooler are currently bypassed.

 

We use the purple simple green you posted.
In your case I would:
1) Remove thermostat
2) Fill with water and simple green
3) Run for about an hour keeping eye on engine temp.
4) Drain cooling system
5) If there is still a good amount of oil in what comes out, do another round of simple green and water, if not move to step 6
6) Remove radiator drain plug, stick hose in degas bottle and let run though for a awhile, starting the truck every few minutes for a minute or 2.
7) Once the water coming out of the radiator drain is free of simple green and oil, continue on with replacement of the cooler.

You may have to do a few rounds of simple green. It will depend on how much oil is still in the system.

 

Thanks Evan!

 

This is great info, thanks @Evan_P

 

I followed Evan's directions above using Simple Green ProHD. Mixed solution to approx 1 part SG to 10 parts water. Two cycles running engine for one hour each cycle.

I have to say, for removing oil it is excellent! My entire cooling system is clean and appears to be free of oil.

Mucho Thanks Evan! This should be a sticky!

 

Glad it worked for you.