Oil temperature observations

[jmsbntz]

I took the Honda (Pilot) to run some errands for the wife this morning and recorded the following oil temperatures with an infrared thermometer held up against the side of the oil filter.
Of course the initial reading was equal to the ambient temperature after the car sat all night.

Initial temp = 85 F.

Temps after the following number of miles, recorded with the engine idling and the hot air from the cooling fan blocked with a piece of cardboard.

2 miles up to 65 MPH to the wife's work place = 143 F.

4 miles up to 70 MPH = 187 F.

8 miles up to 70 MPH = 205 F.

16 miles up to 70 MPH = 209 F.

Not as accurate as a built in oil temp gauge. But I think it helps to illustrate one reason why manufacturers recommend, that owners who make short trips follow the severe service schedule for oil changes.

 

[Mucho_MPG]

Very interesting information. Thanks for posting!

 

[MolaKule]

These temps can't be typical since you blocked the radiator.

Assume the oil temps are 5-10F above the IR temp.

 

[duaneb9729]

These temps can't be typical since you blocked the radiator.

Assume the oil temps are 5-10F above the IR temp.

[/quote
why would a person assume that?

 

[Doug Hillary]

Hi,
jmsbntz - Your temperature measurements are fairly typical. For instance in a V8 (928) Porsche equipped with a very sophisticated cooling and lubrication system (9 litre sump) it takes around 25-30 minutes to get both temperatures to the operating "core" of around 93-95C

At this core temperature a typical 5W-40 lubricant is operating at the low SAE50 range

 

[jmsbntz]

Originally Posted By: MolaKule
These temps can't be typical since you blocked the radiator.

Assume the oil temps are 5-10F above the IR temp.

Not the radiator... I blocked the air from the rear of the fan, from blowing across the oil filter. But I'm sure the actual oil temp is slightly higher.

 

[jmsbntz]

Good that she's not driving one of those! My Pilot holds 4.5 quarts and I'm using 0W-20 in it. Most of the wife's driving is under 5 miles round trip and I wondered if the oil ever reached operating temperature.

 

[Doug Hillary]

Hi,
jmsbntz - I believe that many drivers do not understand haow long it takes to stabilise coolant/oil temperatures is some engines
Some cooling systems are now so sophisticated that they do warm up(reach thermostat "crack" point)very quickly. In most cases when this occurs the oil temperature may be 20C (or more) below this

 

[Steve S]

An interesting point is that the oil reaches a higher temp as it travels through the engine than the sump temps would indicate.

 

[steve20]

45 minutes of crawling along in second gear, on Saturday (temp 75) oil temp = 237 . Coolant 212 95 Corvette

 

[glennc]

I assume the OP meant he blocked the hot airflow from the radiator cooling fan to take the readings and not during the actual driving. In other words he wanted actual readings of the oil filter surface temp, without the extraneous effects of any underhood airflow.

Correct?

 

[LargeCarManX2]

The oil temp runs in the general range that the coolant runs. This is why oil coolers work nice when an engine is taxed such as going up a long grade and the coolant starts to raise.

I find it interesting speaking of oil temps to check out rear-end temps. They are not controlled by coolant, but run about the same as an engine does....most likely by design. But lets say your running down the road, your rear end temps are about 200 degrees.....it starts to rain and they drop to 160. Interesting!

 

[Gary Allan]

Originally Posted By: Steve S
An interesting point is that the oil reaches a higher temp as it travels through the engine than the sump temps would indicate.


It will hang +/- the coolant temp depending on the stress and/or dwell time. You'll reach peak thermal throughput at highway speeds ..but you'll also be at the peak rejection rate. Idling, you'll be producing the least combustion impulses per minute (btu origin), but will also be at the lowest oil flow and the lowest incidental rejection rate. Btu throughput will be its lowest.

The fastest rate of change, in my observations, is from cold start to about 9-10 miles 9-10 minutes. You can then watch it taper off more as you approach equilibrium. Peak normalized temps (at a steady output) occur around 20 minutes.

I could be pushing 219F @ 65 mph and let my foot off the gas to coast to an off ramp and watch the oil temp drop to 191F ..and then creep back up again as I did the return trip.

Exchanged engines reach normalized temps in about 65% the time/mileage and the oil temp typically remains there. The oddity in my observations (on my equipment) is that combined they appear to cool the engine better than separately. The coolant has a much higher flow rate, so the oil sheds btu's and reaches equilibrium with it very easily. This appears to shunt more combustion heat than the cooling jackets alone ..and somewhat unloads them. It doesn't make sense under normal view ..but that's the effect.

Driving at highway speeds unexchanged in higher ambient temps resulted in 210F coolant indications. Exchanged, rock solid @ 205F (normal with 195F thermostat).

 

[[RT] ProjUltraZ]

Originally Posted By: jmsbntz

2 miles up to 65 MPH to the wife's work place = 143 F.
4 miles up to 70 MPH = 187 F.
8 miles up to 70 MPH = 205 F.
16 miles up to 70 MPH = 209 F.

Not as accurate as a built in oil temp gauge. But I think it helps to illustrate one reason why manufacturers recommend, that owners who make short trips follow the severe service schedule for oil changes.


i would think it illustrates why euro cars are spec'd for 10W-40

Originally Posted By: steve20
45 minutes of crawling along in second gear, on Saturday (temp 75) oil temp = 237 . Coolant 212 95 Corvette
that's an LT1, 160F tstat and reprogram the elec fans to come on at 185F (instead of 235F). You won't see over 190F ever again