Sue, in my opinion, no. It is has detergent qualities but it is not harsh, I've never experienced any problems nor would I expect any. I've used Amsoil Engine Cleaner in several engines with only good results also...The "false seals" you're referring to really only show-up in high-mileage, truly dirty engines.
Thansk Scott.
I used Seafoam once in '09, then used the Amsoil Engine cleaner in 2011
For my VX with 81,400k and about 4,000 miles/year, how frequent should I use these cleaners?
THe MMO sounds so good, I'm thinking of throwing a quart of that in too.