Originally Posted By: Ramblejam
-Longest service intervals with OAT inhibitors
Very true... IN OTHER APPLICATIONS. However it was pointed out that there was little change in the recommended interval for the Ford 6.7 vs the Ford 6.4 with the "old" coolant. In fact, ooking at page 2 of
this info sheet actually indicates that some of the intervals are shorter for MCOrange/6.7 than MCGold/6.4, Granted, the differences are trivial (5000 miles) under normal usage, but the severe usage schedule for the 6.7 with MCO is 45k miles, vs 60k miles for the 6.4/MCG. Please understand, THIS is exactly where my initial confusion comes from- Ford is recommending pretty much the opposite of what I'd expect, here.
Originally Posted By: Ramblejam
-No SCA's needed
But they're needed with EITHER choice (oh, except when they are needed if a coolant test is failed). So that's wash as far as this application goes.
Originally Posted By: Ramblejam
-Better heat transfer
OK, that's the kind of thing I was looking for (finally). I would love to know any specifics on why the heat transfer is better with an OAT vs a HOAT. I only ask because the bulk coolant is still water and glycol in both cases, so whatever difference there is has to be pretty specific to the chemistry at the coolant boundary. What's reducing heat transfer in a silicate/nitrite additive package compared to an ELC, when in fact the nitrites increase the effective thermal transfer by preventing steam pockets and microbubbles at the coolant/metal surface? Does the silicate component negate the advantage of the nitrite? Presumably ELCs have a similar mechanism, and maybe even better... so my curiosity now wants to know HOW the ELC mechanism works.
Originally Posted By: Ramblejam
-Reduced dropout/scaling
If the 6.7 design is going to go ahead and continue to overheat the coolant the way the 6.0/6.4 EGR coolers did, then I unconditionally agree that it is true that a non-silicated coolant has at least a slightly better margin against precipitation during that kind of abuse... but it wouldn't make me comfortable to think that they're still doing that to the coolant. And *that's* why I posted the 200k mile picture you dismissed as irrelevant before- as proof that there is not any dropout or scaling with G-05 EXCEPT when a design flaw abuses the coolant. Heck, that was even true of IAT coolants, but you did have to change them more often. No matter what the coolant, you have to operate it within accepted engineering bounds, and that was the failure of the old-design Ford EGR coolers.
Originally Posted By: Ramblejam
-Longer water pump life
Also a likely factor, but I've had trouble verifying this beyond people on the internet saying so. Back in the IAT days, the silicate additives were actually touted as being water-pump *lubricants* (which they were, until they degraded), but today people seem to equate "contains silicon compounds" with "abrasive." and that isn't true- it depends on the compound, not just the presence of silicate groups in a molecule.
And you left off "lower cost" and "expected tightening of environmental regulations" that might affect coolant manufacturing and disposal. Those may matter more than anything else, honestly.
Thanks for the answers, and obviously I don't entirely agree with all of them. But I do appreciate something more concrete than "new is better."
