"Smokeless" 2T oils have been available for a while now, so doubtless, control of such tribological tell-tales are well in hand...
http://www.maximausa.com/product/super-m/
&, as the O.P. noted, the use of metallic compound additives ( such as lead naphthenate) in consumable lubricants to both improve wearing component lubrication/durability & act as a fuel efficiency catalyst has been long known...
https://www.google.com/patents/US3348932
More newly discovered is the ability to use nano copper/carbon catalysts to convert CO2 to ETOH,
(& possibly within a running ICE, using selective cylinder process activation?)
I guess a swab scraping/gas sniffer probe to the exhaust outlet might be 'illuminating'...