The damage in the first few seconds of engine running must be almost totally related to the oil used. And I wonder if this is a fossil recommendation from the pre-multigrade days?
Wear and damage are different animals. Wear during initial engine start is always an important consideration, but if you're not using a pre-oiler, you're not giving it consideration anyway, temperature not withstanding.
Preheating is not a "fossil recommendation." If you care about your aircraft, it should be mandatory. Anytime you're below about 40 degrees F, you should be preheating.
Preheating isn't just about keeping the oil flowing. The entire engine should be preheated, not just the oil.
Aren't there heating devices which go into the oil dipstick hole?
Dipstick heaters tend to be too hot, and can damage the oil. Oil heaters that span the bottom of the sump are also available, but still do nothing to heat the engine; just the oil Tannis sytems that encircle each cylinder and warm the engine and the oil are much better, and should be used with a shroud or blanket that covers the engine nacelle to retain the heat.
The poor boy engine heater is a work trouble light laying on top of the cylinders, with a blanket over the engine.
Combustion space heaters with a hose to the engine compartment also work well, but it's far better to have the engine stay preheated all the time, rather than start heating the engine before the flight.
A "fossil system" is oil dilution, which was factory-installed in some aircraft, standard in some, optional in others. It involved running avgas into the oil prior to engine shutdown, in order to reduce oil viscosity. In theory, the avgas would vaporize and allow the oil to return to it's original state after the next engine start.
Dilution changes oil chemistry, leaves deposits, and adds a solvent to a lubricant: never a good solution. Nearly all oil dilution systems have been removed or deactivated today.
Removing oil from the engine and keeping it warm, then returning it to the engine is a necessity when temperatures will drop enough to congeal oil. This still doesn't heat the engine throughout.
The engine is made up of various metals, each of which have different expansion rates. The entire engine should be heated uniformly, as best able, prior to engine start, for cold weather starts. Adding heated oil to the engine doesn't accomplish this, but does at least get oil flowing during the initial start, which is better than not having the oil flowing.