I like Seafoam too. On the gassers I pull a vacuum hose and stick it in the can, moving it up and down to keep the engine from stalling. Once I am near the bottom I let the engine suck up enough to stall, then wait about 5 -10 minutes before cranking it up. You should see the clouds of carbon that come out then! A quick drive down the highway (fogging all the mosquitoes as I drive by ) and the top end of the engine is clean.
I just did the Suburban the other week and now it is the Jeep's turn...

I have not tried pouring it into the crankcase, but with my engines hitting 200K miles I am very cautious about additives in the oil.

For Diesels I use the LubriMoly Diesel Purge running the engine straight off the DP. That works great too...

Hope this helps :-)

__________________
"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy"

Current
Monika '74 450 SL
BrownHilda '79 280SL
FoxyCleopatra '99 Chevy Suburban
Scarlett 2014 Jeep Cherokee
Krystal 2004 Volvo S60
Gone
'74 Jeep CJ5
'97 Jeep ZJ Laredo
Rudolf ‘86 300SDL
Bruno '81 300SD
Fritzi '84 BMW
'92 Subaru
'96 Impala SS
'71 Buick GS conv
'67 GTO conv
'63 Corvair conv
'57 Nomad