A while back, I bought a few sets of NOS AC R44 made in Gt. Britain, sometime in the 60s.
They still have painted rings on a saw-blade-ribbed porcelain.
Easy to distinguish from the newer AC plugs.
You can't go wrong with the shop manual's recommendations.
I used to always go with the R45S the parts stores offer for late 235/261, but I like the stock plugs better.
It felt the same when I started using straight grade oil.
Temps get pretty high after a couple of hours on CA desert freeways this time of year.
The right choice depends on your driving and climate conditions and reading the plugs.
For mostly city driving and colder winters, the hotter AC 45 plugs and multi-grade oil would be better.
It's funny though, at the end of the day, it's amazing how well these engines run, even if you don't get them ideally tuned.
Then again, she truly wakes up and just keeps on going, if you give her what she likes best.
