I'm cleaning and re-oiling the "Falls Filtration Technologies" type P1S air filter on our group owned Aeonca Chief.
Servicing instructions stamped on the filter say " Dip in engine preservative oil conforming to Grade 1 or 2 of Mil-L-21260 & allow to drain etc .
Could anyone advise which oil would be suitable?

I've checked the relevant "Mil-L-21260" but this doesn't seem too clear.

Thanks!

Ian