Originally Posted By: oil_film_movies
Originally Posted By: SonofJoe
Your Honda factory fill oil will be as good as it gets. Changing to another synthetic won't help you one iota. If the fuel dilution issue persists & bothers you, maybe move to a 5W30. With the
fuel dilution, it will over time 'thin' to around about a 0W20.
Mobil1 AFE 0w30 prescribed here. Yes, go up one grade in this case.
Too much of the engine gets boundary lubrication when kv100 is 5.
Originally Posted By: SonofJoe
If you're feeling adventurous, talk to Honda about replacing the radiator cap; one with a higher temperature set-point. It might be what this engine needs to purge the condensed gas from the sump.
Do you mean go to a higher Fahrenheit thermostat? Cap is just a pressure vent for when things get really bad.
Regarding radiator caps & thermostats, I have confessed on many occasions that I don't do 'mechanical'! The last time I actually took off a radiator cap was probably in 1978, on my old Austin 1100. My recollection back then was that the thermostat (which restricted the flow of coolant to the radiator) was a simple bi-metallic thingee integrated into the radiator cap itself. I humbly accept that things may have changed somewhat over the ensuing four decades!
But my point still stands. If the coolant thermostat is set too low (say 80°C) then in all likelihood, it will keep the engine oil temperature too low and any fuel dilution will be glacially slow to purge itself. A higher thermostat setting (especially in winter) might offer a 'cure' but only for longer distance drives. Obviously if you just pop down to the shops & back, the engine won't warm-up regardless of what the thermostat says.
Regarding 5 cst and boundary conditions; I don't think you can say that definitely. If you got the engine oil upto 150°C then I would absolutely agree with you but at that temperature, any gasoline would quickly be purged, so the oil's viscosity would revert to a less diluted, more normal level. At 100°C, hmm...I think your HTHS would still be in safe territory for the bearings. At an oil temperature of 80°C (which I think would be more consistent with driving in the kind of bitterly cold conditions that promote fuel dilution in the first place) then the KV of the oil, even with lots of fuel dilution, will be relatively high, so boundary conditions will almost certainly be avoided.
I tend to regard fuel dilution as God's way of helping engines in cold weather. Fuel dilution bought on my extreme cold will deffo help with cold startability and improve fuel economy during the warm-up phase.