optimal engine oil temperature

[piusk]

looking for best oil temp for auto/truck under load in towing mode. 200 seems too low for evaporating any moisture.
230 seems to be getting high. gasoline engines.

 

[stout1]

no 200 is not too low for the temp. It's going to be running at whatever your engine water temp is set for (or close to it). I would give a better explanation but I'm not fully awake yet. Are you having problems with water in the oil? Is there something wrong that you feel the need to change things? Or are you just curious?
Have a good one.

Michael

 

[Fabrico]

It depends on the application, but evaporating moisture is not at the top of the list of things engine oil needs to do. An engine works hard while towing. The best temperature is one that lets it do it's job lubricating and, at the same time, help to cool things.

 

[amorrison]

Slightly off topic.

Oil vs. engine coolant warmup time.

In an engineering article I read 20 yrs ago it said that the coolant warms up in ~10 minutes but the oil takes ~30 minutes.

IMO this doesn't make much sense as a large part of the oil is in contact with the engine block interior surface (dripping down from the rocker arms etc) so I think both fluids would be ~ the same temperature.

Comments.

 

[drwebb]

I have run a data logger on my air cooled street motorcycle and the top end doesn't reach operating temperature until fully 20 mins of riding, so 30 mins for a W/C 4-wheeler is very plausible to me. Most of the oil is in the cooler sump and only a small portion gets pumped to the pistons & top end, whereas all the coolant gets quickly circulated to transfer heat.

Also noteworthy, the top end rises about 15 C to its highest temp immediately after shut down when all the heat has nowhere else to go but up, so the most thermal stress on the lubricant occurs when the engine isn't running.

 

[Fabrico]

The only suggestion that oil cools everything, is by statements about it's irrelevance in doing so. Even in low output engines, oil has a critical role in keeping the temperature of various components of the valve train at tolerable levels. Valve springs, stems, tips, followers, etc all depend on oil to carry away heat. High output engines use oil for direct cooling of pistons and cams as well.

Engine oil cools things two ways. One is by carrying away heat in its circulation. The other is by conducting heat rapidly from one surface to another such as a valve-stem to guide, or cam-follower to block. Thinking the temperature increase of the top end after shut down is entirely because it "has nowhere else to go but up" is a bit green.