Graphite in Engine Oil? Let’s Watch
Russ Chastain 11.24.20
(Image: Screenshot from video)
In this video, product tester Project Farm does some experiments to determine whether there’s any benefit to adding graphite to engine oil.
It’s well-known that graphite is a good lubricant, but it’s also referred to as a “dry lube.” Heck, I often rub a pencil lead on my guitar strings where they pass through the nut, so they don’t stick when I tune the guitar. But how will a dry lubricant work in conjunction with a wet one?
To test it, he uses some old Arco brand oil from the 70s, which was sold with graphite mixed in. It claimed to improve gas mileage and reduce wear on piston rings & cams. He compares it with a modern oil of equivalent viscosity, and even does a test in which he adds powdered graphite to another modern engine oil.
The Arco graphite oil looks terrible, it’s so dark — and after being heated to test evaporation, it even appears sludgy. But in a wear test, it definitely provided much better protection between two steel parts than its Quaker State competitor.
The sludginess makes me hesitant to consider using graphite oils in a pressurized oil system, because it seems likely to clog up the oil filter and put a strain on the oil pump. But in a splash-type system in a small engine, it may be pretty dang good.
In a fuel-injected generator, the Arco failed to increase fuel efficiency.
It’s an interesting comparison, and the presence of a bunch of zinc probably helped the Arco a lot in the lubricity test… but I think I’ll just stick with straight 30w diesel engine oil in my small engines, as it’s supposed to contain a lot of zinc. How about you?