I posted this message in another thread about engine break-in, but I thought it would be worth raising the question in a thread by itself.

Reed and I, since we installed the oil temperature gauges, have both noticed that the oil temperature is about 127 degrees F at the moment three bars light up on the stock temperature gauge. Normal oil operating temperature, we have also recorded, is above 190 degrees, and goes consistently over 210 when the engine is being pushed. So the engine and oil are far from fully warmed up even when there are three bars on the stock temp gauge. I watch the oil temperature gauge now and don't push the engine or V-TEC until oil temp reaches 170 degrees, which takes a few more minutes after three bars register on the stock temp gauge.

Does any body know whether we should be concerned about the oil reaching nominal operating temperature before we push the car hard?

 

Interesting observation Rick. I normally don't VTEC my car until several minutes and a few miles have passed after hitting 3 bars. IMO, pushing the car before the engine is fully warmed up is not a good idea. I give it extra time even though the 3 bars are there.

Actually, I am not VTECing my car at all right now.......it only has 400 miles on it

 

I don't know if your temperature readings can be directly translated into whether the engine is properly warmed up yet. As you know, engine oil contributes one of the ways engines are cooled. In a nutshell, parts of the engine that need to be cooled aren't near the coolant and are cooled by the oil. For example, how does the coolant cool the pistons and crankshaft? They don't. Oil is the only thing that can do this.

Also, keep in mind what an engine is. An engine is a device that takes fuel/air and changes it to exhaust while spiking the temperature up several hundred degrees. This means that *every* cylinder ignition causes a rather sudden fluctuation of temperature. Far more than 80 degrees oil temperature difference you've measured. Therefore the engine *has* to be built to work fine at rather significant temperature variations.

Also remember that the oil pan contains 5? quarts of oil. It takes a bit to heat all this oil up, even though the running temperature of the oil in the engine might be close to correct temperature. The pan temperature might be 127 degrees, but the oil in the engine itself might be within 5-10 degrees of the correct temperature. Just a thought.

I suspect that the major reason for not running the engine hard on a "cold" engine has to do more with the viscosity of the oil and whether the oil is sufficiently distributed in the engine. In addition, I suspect the oil pressure run VTEC cams may not work properly until the oil reaches certain temperature/viscosity.

 

I think that this might be a case where a little too much information is a bad thing. It's known what the "operating" temp of an engine is as it relates to coolant temp. But do we (non-mechanics, non-engineers) really know what operating temp is as a measurement of oil temp? We know that there is a threshold "low" temp where oil doesn't flow or pour very well. Is there a threshold "high" temp where oil begins to flow and pour differently? Or is it such that after a certain temp, oil simply flows the same regardless of further increments in temp? And once 3 bars are reached on the temp guage, has the oil reached or gone beyond it's optimal flow characteristics? I've never worried about this before. Should I start to worry about it now? Maybe Honda designed this engine such that once three bars are reached, the oil temp and flow characteristics are acceptable to go beyond 6K rpm.

 

I would hope that since three bars on the temp gauge is normally the maximum temp seen, that three bars are safe for high RPM operation. Honda must think so, too, since VTEC is not possible below the three bars. They must have a slight margin for over-eager revers.

 

my car will VTEC on two bars; not that i know this firsthand or anything. i just must've miscounted that time.

 

i never Vtec until about 1 min after 3 bars are reached on the temp gauge

 

Yep...same here...maybe a 2002 thing??

 

That's interesting. I've got in the habit of not vtecing until the gearbox feels warmed up. There's a nice improvement in the 1st gear shift in particular. I find this takes a few miles at least after 3 bars. I'm installing the Spoon cooling parts soon - I guess leaving it a little longer after that should help see the oil at operating levels.

-Brian.

 

The VTEC switchover logic (as is the temp gauge is tied to coolant temp... Not to engine internal or oil temps. Personally, I'd wait a few minutes after the 3 bars is reached.