Have heard of various leaning techniques beyond the traditionnal "enrich once at EGT peak"
Finally, I found on the web those advices from a senior pilot who affirm you won't kill your engines by leaning to get a 50 F drop on EGT
Here is the link
http://www.avweb.com/articles/pelperch/pelp0042.html
Have tried on the Seneca am flying every day, seems to save some fuel and numbers look fine (EGT, CHT, F.Flow )
So what are you views , wise techies ?