Oil catch can install? Seafoam?
2. vehicle use
3. has the engine ever been open (besides oil cap or valve cover)
4. do you see oil in the intake tract
5. have you inspected the pcv tubes for oil
6. do the plugs show any sign of oil
What do to:
1. do a compression test as you replace the plugs, WRITE THE NUMBERS DOWN. get the accurate as possible i.e. 134.5, 136.8, etc... use decimals even though it feels kinda dumb
2. If you don't find any oil in any of the ducts/tubes/intake then there is no need for a catch can. You can add one for just in case value (if something fails and oil comes gushing out it has somewhere to go) but adding length/plumbing to the pcv system will slow it down to some extent so it is only recommended to add if you need one.
3. Remember to use high quality fuel filter, and an OEM paper filter with the OEM intake duct if this is a daily driver with an engine you care about
And as to seafoam. Depends on many factors how effective it will be. IMO a better long term solution is to spray distilled water (with a meth/water kit) to help clean up the engine's insides. Seafoam is fleeting. Although it seems like it would remove some of the buildup, I feel like you would need 10 bottles of the stuff to do any real cleaning.

