Hey Jacknasty, I have heard of things like that happening- I'd maybe give a synthetic another try- You can really get some garbage build up in an engine over time- are you running a K&N? They let a lot of crap pass through. I have one in my Tundra but I have several associates who have sworn off...
AMSOIL now has seal swellers, but I haven't upgraded to it just yet. Yes I'm biased as I've been a 'dealer' off and on for years but never did much except subsidize my own habit. I think the tranny will be the first to switch over-