...what's to keep the new ones from seeping as well? Did you use any kind of sealant? Silicon, Permatex, etc...?

 

I dunno. In fact, that brings something up. When I put my new spark plugs in I started to get a lean code. Reset adaptations and it was gone... then it came back after a week or so. Rinse, repeat. I was baffled that new spark plugs would cause a lean issue. Then I realized I had put these buggers in. And they are BritPart which is total crap, one step above URO but its all RockAuto had at the time. So I suspect two things. One, my seals may be crap. Two, I noticed the solenoids had surface rust/stuff so the new seals may not be 100% sealed against the solenoid.

Thus my thoughts are a super thin coat of Renzoil. So no, when I put them in I did not use anything but I think it might be a good idea. I think normally they just leak from age, probably shrinkage/hardening of the rubber material.