Wanted to share with those folks who wish the older BDM had a dip stick on there push in oil cap I use to be one of those folks. Here's a pic of mine. The stick and cap have a m6×1.0 thread.
I used my current oil cap.the chrome cap is just glued to rubber. Remove it and tap a m6×1.0 in the hole that's already in the cap I purchased a 6mm rod of polyoxymetheline on Amazon. Thread it the same size as cap.