Turns out I was looking in the wrong 'hole'. The vernatherm was in an
extended housing on the bottom side of the oil filter adapter and did
contain a vernatherm. However the seat at the end of the plunger was
unevenly worn, with one side worn in a bit and the other side showing only
slight contact. My mechanic is ordering a new vernatherm and will also
resurface the seat inside the oil filter adapter. If that doesn't fix the
oil temp, I'm going to have the oil cooler removed and flushed by Pacific
Oil Cooler or someone equivalent.

Anyone have any good or bad experiences to share with oil cooler cleaning?

--
Regards,
Mike

http://mywebpage.netscape.com/amountainaero/fspic1.html
wrote in message
om...
My 1975 172M (Lyc 150 HP O-320E2D) likewise had no vernatherm when I
checked. It apparently must be common to leave them out as they are
expensive. I don't have a problem with oil temp except that it many
times runs too low. Do you have high oil temps?