I've now ruined probably about 7 t-shirts by getting huge circular lanolin stains on them. I didn't realize that it was seeping through my bra :. But maybe they're not ruined? Is there anyway to get lanolin out?
For removing lanolin from fleeces (I'm a handspinner), I use plain old Dawn dishwasing detergent. I forget what the ingredient is, but it's a less concentrated version of what's used for commercial scouring of wool.
Anyhow, throw those shirts in a hot hot wash with a good squirt of Dawn & let 'em sit for 15 minutes or so. Rinse well & dry. Should do the trick. If it doesn't, then I'm out of ideas.