Most car owners know to get their oil changed every three months or so. (And yes, just because you personally don’t change your oil every 5,000 miles doesn’t mean you’re not supposed to.) But just how important is oil to an engine’s health? More importantly, what happens to an engine when there’s no oil at all? Engineering Explained takes a look at two very different instances — an engine running on 10W-30 oil compared to a bare, oil-free block. He breaks the analysis down into observing several parts of the engine. Number 1 is the bottom of the crankcase, number 2 is its top. Number 3 tracks the block itself. Number 4 looks at the exhaust pipe’s temperature. Lastly, Number 5 tracks the valve cover.
It takes about eight minutes for the engines to calibrate to running at nearly identical conditions. While the temperatures at the exhaust point seem equally matched, the evident differences come when looking at the two readings from the crankcase. There’s little to no temperature difference when comparing 1 and 2 on the right-hand side. This is because there’s only air on either side.
So what are the overall findings? Surprisingly enough, there isn’t as big of a temperature difference between the engine having oil and the engine lacking oil. This might go against any motorhead’s intuition, as oil changes are harped on so frequently. Oil should reduce the friction in an engine, thus greatly reducing the heat created by those rapidly moving parts. However, that drastic difference isn’t what the video shows.
Does this mean you can cool your engine by running it without oil? Far from it. The lubrication provided by oil is still crucial to an engine’s overall health. Unsatisfied with the results, he cracks open the crankcase to see if anything else changed. The residual oil that pooled at the base of the engine showed a lot of metal flakes when compared with the residual oil left over from the oil-filled engine trial. The rotator bearing for the crankshaft also showed significant wear and scrapes from the lack of lubricant.