I am also dealing with Cetol, but in the removal process. My exterior teak was au natural for the first 30+ years before being covered with Cetol, so there are lots of grooves from the grain of the wood. I am working on taking off the layers of Cetol and going back to teak oil.
I have to take the wood back down to a level surface to get all the Cetol off, and I am using a palm sander starting with 50 grit and finishing with a finer grit, so far with pretty good results. The polysulfide under the caprail needs replacing, especially at the lowest points of the curve. The question is, do I re-oil the teak before I apply the Life-Calk or after? I am digging out the old stuff today, and planning the next step. I am giving the area a good scrub with a nylon scour pad to prep the surface so the caullk adheres well, but I don't want to put the oil on only to find the caulk won't stick to it.
As always, any suggestions are appreciated,
Stephen