A theory I have been kicking around involves the coolant flow through the oil cooler to the egr. With the high heat of exhaust being transferred to the coolant, could it be possible that the resulting pressurized coolant could be reducing flow through the oil cooler FIRST, and that along with the coolant system's ability to efficiently scour the block's every nook and cranny of debris which in turn finally ends up in this resulting low flowing pocket that is formed (oil cooler) effectively turning it into a filter ? Why not the radiator ? Heater core ?
Why do I see some of your trucks coolant filters load up with slime, while others (mine included) are spotless ? Could air be entering some engines through suction leaks, causing the inhibitors to be used up quickly ? Could this in turn be the cause of the silicates dropping out of suspension, that it is "filling in" the bare metal at the point of corrosion and being spent ? In other words could this potential point of corrosion be the problem, not the coolant ? For those with particularly bad coolant filters, maybe be on the lookout for a damp hose connection, or gasket joint. (water pump) Any thoughts ?
As for coolant types, I am on the fence as well. I feel that the issue of coolants is on the front burner of every engine designer right now, especially with all the composite materials being introduced to make engines lighter, along with that egr thorn.
Out of curiosity I pulled some data from a couple of coolant types being discussed here. This is the ASDM D1384 glassware corrosion test. Both show good numbers but,
The first is Shell ELC.
SHELL ELC CORROSION INHIBITOR
If you page down to the ASDM corrosion test, it shows the aluminum loss at 9.8 mg
The second is Zerex GO5
http://www.whitfieldoil.com/download...G05Formula.pdf
It shows a negative 2, (a gain) which may be indicating added weight possibly from the silicates. This may be trivial, I don't know. But it may warrant checking that ELC every now and then as well, not just dump and forget. We do have tons of aluminum in there.
Just to throw a wrench in, Deere & Co have also been introduced to the wonderful world of EGR's. Here is their solution.
http://www.landmarkimp.com/images/homepage/coolgard.pdf
A tri oat formula without the nitrates like ELC, but I was told it still contains low silicates. Go figure.
As for my truck, I figure I will monitor that filter and the nitrate load closely along with the ECT &EOT and switch at the first sign of trouble, but only if the entire coolant system is sufficiently healthy.
On my Deere tractors with wet sleeve liners, I have always been able to wear the rings down first, with no cavitation damage on those engines (common) with plain old low silicate AF, test strips, and nitrate additive. It may be prudent to "babysit" these new coolants as well.

 

Very good discussion of this over on another site. Here is a link.

Silicates in the cooling system... - PowerStrokeNation

 

Good question. I remember this same kind of speculation back before Ford had approved 5W40 oil for the 6.0L. Ford eventually did approve 5W40 in early 2008 IIRC, which coincidentally (ha!) was around the same time Motorcraft came out with a diesel 5W40 oil.

I think it all boils down to the bottom line.

 

I was thinking the same thing. However, there are so many cases of issues w/ silicates, I would have thought that they would have started approving non-silicate formulas by now. As you said, they approved the 5W40 oil quite some time ago. Plenty of time to work w/ suppliers and get a Motorcraft branded version of ELC coolant (if they don't have it already).

Great discussion - thanks to all.

 

I'm not sure there are a lot of documented issues w/ silicates. My engine had oil/EGR failures, even though I adhered to--actually, exceeded--Ford's recommended cooling system maintenance. I have my old oil cooler and there's definitely some sandy looking stuff down in there, but I cant be sure silicate dropout contributed to the problem. Could have all been due to casting sand and/or rust for all I know. But why take a chance? From what I've gathered, silicate-free full carboxylate ELCs have superior corrosion inhibitors to other coolants. I'm sold.

 

Wow, that was like reading about a cat fight!

After about 13 pages of insults I learned that we have to maintain our cooling systems and ELC will last longer between changes.

 

LOL!

I learned that we don't have much silicates in the coolant, but I don't think it would take much to complex with other components and form goo.

Clearly they emphasize proper maintenance, but there are still a few mysteries around the coolant debate!

 

I'm not convinced the guys who report silicate is responsible for plugging their oil coolers know the difference between casting sand and silicate.

BTW... That was a hilarious read over at PSN...LOL

 

It also seems there is a large number of t-stat failures.
I don't think I've EVER had a t-stat fail on any vehicle I've owned?