Thin vs. thick: cold-engine protection

[sk_pete]

thankfully i don´t have f1 engine, where must circulate hot fluids for several minutes (before start), because of too tight tolerances...
sane person would not jump too high with viscosity... like from 0w30 to 20w60,,,
people should watch engine production lines, inspection runs them at full blast, either it will survive or will be scrapped. no run-in.

 

[ZeeOSix]

The problem is not only because the shaft and housing have different thermal-expansion coefficients. Even if they have identical thermal-expansion coefficients, during warm-up, there is a large temperature difference between the two before the steady is reached, which reduces the bearing clearance because the shaft runs a lot hotter than the housing. Combined with a very thick oil, this could result in oil starvation and wear during warm-up.

A positive displacement oil pump is used on engines for a reason. Journal bearings aren't going to be oil starved as long as pressurized oil is supplied.

If oil starvation on cold start-up was a problem, cars in very cold climates wouldn't make it past 50K miles without needing an engine rebuild.

 

[Zaedock]

thankfully i don´t have f1 engine, where must circulate hot fluids for several minutes (before start), because of too tight tolerances...
sane person would not jump too high with viscosity... like from 0w30 to 20w60,,,

Too tight tolerances, huh?

 

[ZeeOSix]

Also, any good engine designer is going to take into consideration the most extreme cold start-up conditions, and testing done to ensure no engine damage nor excessive wear happens. ICEs have been around a very long time, and have been started up and ran in extremely cold environments for 100 years, with motor oils not nearly as good as the oils available today. Engines today wouldnt last 200K-300K or more if cold start-up wear was worth even worrying about.

 

[930.engineering]

IMO, waiting 15 seconds to a minutes just to be sure that oil pressure is there

While I do read this quite often on this forum I don't get it. Full oil pressure is there within less than one second. Admitted, some valvetrain parts may require some more time for full lubrication, but that's not oil pressure.

people should watch engine production lines, inspection runs them at full blast, either it will survive or will be scrapped. no run-in.

Pete, please don't follow popular forum myth. Did you actually watch any production line yourself? I didn't see any single production line where all engines are run on fuel, whether run 'full blast' or another way. On any production line I've seen in person recent years all engines are tested without a single drop of fuel - driven by an electric motor. Only a very small number (don't remember exact number, but certainly one of several hundreds at most) will be run on fuel and/or disassembled for quality control reasons. This is the case at all current German manufacturers at least. Hard to believe huge American and Japanese companies do it any different. Using fuel isn't needed in 2021 and isn't reasonable due to safety concerns.

 

[OM605]

While I do read this quite often on this forum I don't get it. Full oil pressure is there within less than one second. Admitted, some valvetrain parts may require some more time for full lubrication, but that's not oil pressure.

That's true and what i am saying, it's just that i don't really like to drive it cold without waiting for the RPM to drop or at least 15 sec but that's just me.