My tankerman dl and lg has been expired about 10 years how can you recertify
http://www.dco.uscg.mil/Portals/9/NMC/pdfs/checklists/mcp_fm_nmc5_01_web.pdf
http://www.dco.uscg.mil/Portals/9/NMC/pdfs/checklists/mcp_fm_nmc5_57_web.pdf
You can only renew an endorsement within one year of its expiration, see 46 CFR 10.227(b), see also the note on those checklists linked above that states “ONLY if not expired for more than 1 year.”
So you can’t renew the long-expired endorsement, you have to qualify for it as an original endorsement.