yeah, all the old school rules are still quoted here.
Take it from a fleet owner of GM vehicles, many with super high miles.
Use any high end synth and filter, and do it when the OLM tells ya.
Anything else is wasting your money. I have vehicles running 6 days a week with 400k miles and 250k miles on them that we only follow the OLM on.
No smoke, no consumption, and no drips.