ArcaMax

Everything changes - even oil changes. Not necessarily the procedure. But the oil you use. Or rather, ought to be using. If you happen to own an older vehicle.

https://www.youtube.com/watch?v=u1KOElr2nkc&feature=youtu.be

Specifically, a vehicle with an engine that has a flat tappet camshaft. Which is - pretty much - every American car with a V8 engine made prior to the early 1980s (at which point, roller cams began to come online, first in cars like the Mustang GT and 5.0 LX of that era). But what is a "flat tappet" camshaft?

It's actually not the camshaft, per se, that's the important (in terms of this discussion). It is the tappets - the lifters that get tapped (well, pushed up and down) by the cam's lobes as they rotate. The contact surface of these lifters is flat. One of the reasons - the chief reason - why flat tappets were thrown in the woods (retired) in favor of roller lifters is that roller lifters allow more aggressive cam lobe profiles due to the more favorable geometry.

Instead of pushing up against the flat bottom of a flat-tappet lifter - which places increasing pressure/stress on the flat surface of the lifter's bottom as the eccentrically shaped cam lobe rotates to its "pointy" end (peak lift) - the cam lobe in a roller lifter scenario contacts a nearly friction-free roller on the bottom of the lifter that allows much more aggressive cam profiles with much less pressure/stress (and friction) on the valvetrain.

Anyhow, the issue is that older engines with the flat-tappet layout require certain anti-friction additives in oil - zinc dialyldithiophophate, or ZDDP - to avoid rapid wear and premature failure of the valvetrain. The problem is that the ZDDP has been all-but-removed from most (if not all) commonly available/over-the-counter motor oils, in part because modern engines with roller-type camshafts don't need ZDDP but chiefly for emissions-related reasons.

https://www.youtube.com/watch?v=-EqzhHewZqY&feature=youtu.be

All engines - even (especially) brand new ones (during break-in) consume a little oil as they run; the byproducts of that consumed (burned) oil - including the additives, now in gaseous form - become part of the exhaust stream.

Before catalytic converters, which came online in 1975, this was ok. Well, it wasn't a problem (other than the occasional puff of blue smoke). The gasses - and whatever they contained - went out the tailpipe and were no longer your problem. Since catalytic converters became mandatory standard equipment - and especially since federal emissions laws became downright Stalinist in the early 2000s - the ZDDP additives in the oil became a problem because they tended to accelerate the functional degradation of the catalytic converter.

Which the feds now require the car companies to warranty for 10 years/100,000 miles. If the converter stops doing its converting before that time/mileage interval, the car company is on the hook for all or some of the replacement costs. Lots of bucks on the table.

...continued