Sometimes, short responses are hard to decipher.
It's hard to tell what Tom is replying to when he says:
"It should be, that is a fire retardant so the whole filter won't go poof when exposed to a back fire."
...but we are assuming he's talking about the spray that is applied to foam air filters. As far as I know; Brackett filters are filters, that come with oil already applied, if necessary. I haven't found Brackett oil; it might exist, my short google search didn't find it.
https://www.aircraftspruce.com/catalog/eppages/brackettairfilter.php
In the accessories; it lists no Brackett oil that you can buy. It does state that "The specially treated polyurethane element in the Brackett filter assures near total protection from any foreign material entering the system. Repels water, fire retardant and has good air flow for proper fuel/air ratio. Has no pleats to collect dirt." It reads like they are talking about the polyurethane element; not the spray? NOTE: I am not an A&P and am not trying to be. I'm just a guy on an internet message board; replying as the forum rules allow.
Salty replied:
"I thought it was to aide in collection of particulates."
Tom said:
"That too, primary = fire protection."
Now; if we're talking about the spray that is applied to foam air filters, I think Salty has a point. The primary purpose of the spray is to aid in collection of particulates (that's why I've always used it on my dirt bikes foam air filters). I buy a special filter that aids against backfires; but I put on the spray/oil to try to get more dust in the filter, less in the engine. I think that's most people's use of air filter oil; is to get more particles in the filter, less passing through into the engine.
If we're talking about the polyurethane; then I'm on Tom's side. I think fire retardant is one of the primary purposes.
Enjoy the beautiful day guys!