First, you cannot apply a borate unless you have bare, unstainedwood, so don’t waste the money.
If you have the old Sikkens Cetol 1 & Cetol 23 stain on your house now, you should use Cetol Log & Siding. If the original stain was the Sikkens SRD, then I would use that product. You should ask a Sikkens dealer formore application advice if possible