Originally Posted by Impatient
So, if a manufacturer changes specs, is it safe to use the newer spec? In my case, could I, or should I put the newer blue Subaru coolant in a 2007 ( these things have known head gasket issues )..
In the case of the Suby , yes if you want to. The newer blue premix is a long life, long service interval PHOAT as opposed to the older green which was a shorter interval AF. Looking at Suby forums, Subaru has said the newer blue is backward compatible. Toyota (pink SLL for red) and Nissan (blue LL for green) did the same for their AFs. The Suby head gasket issues afaik unrelated to the AF used.
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...and likewise, the newest yellow Ford coolant in a 2015 3.5 EB? Ford says if your orange Ford coolant has clogged/corroded your heater core, you SHOULD change to Corguard (why not yellow Ford??), along with replacing the heater core) but they won't change it for you unless it exhibits certain problems before 36k; after that very expensive out of your pocket, despite TSB. They have not back-spec'd yellow coolant for 2015's as far as I know. And then both manufacturers say never mix coolant types. Sort of contradicts the "universal" theory.
With some googling effort I was able to find the specific noted Ford TSB, and currently it only specifies ONE Ford model vehicle, the 2015-2018 Transit.
https://ford.oemdtc.com/TSB/18-2172.pdf
As for the 'new' (D)Yellow Motorcraft AF, currently it's only spec'd for the newest Ford trucks, Econoline, Transit and Expedition/Navigator. As noted the current MC AF chart indicates it's not back spec'd for anything. Until or unless that changes, I would NOT assume anything else to be true including using it older Ford Orange or older Yellow AF spec vehicles. Nor 'at this point' would I assume that the current Prestone labeled AF should or could be used in place Motorcraft Orange (dex) or the new D-Yellow AF. In other words, until more definitive info out there I wouldn't assume anything beyond the specific tsb reference.
It does make me wonder if this is more a Ford/Ford Transit heater core manufacturing issue, than an AF issue. Also wonder what the D prefix Yellow Motorcraft AF stands for. Maybe Dark Yellow? The other "Yellow" is G-05, they call MC Gold is more a light Yellow/Gold tint. With this latest AF addition to the Motorcraft line Ford AF is
. I thought they were set with the Orange Dex AF, apparently not.