Oil temperature - where does one measure this temp?

[John M.]

Where on a small block Chevy is the oil temperature measured? the C4 was the first Corvette I can think of with an oil temp readout, and I am certain the C5 has this feature as well. Is the temp taken in the oil pan or somewhere while the oil is under pressure and on the way to vital engine parts, or at the oil filter? Any information or facts appreciated and anxious to have your experience or input.

[Jim L.]

Re: Oil tempreture - where does one measure this ttemp

Where to measure depends on what you want to measure. Seriously. Are you interested in oil temperature after the oil has dribbled off the rocker arms? Do you want to know the temperature of oil as it dribbles off the flat tappet cam? It all depends on what you want to know and I don't mean for that to sound like a smart ass answer.

On my vintage racer, I'm content to have the temp sender measure the oil in the pan.

Jim

[David H.]

Re: Oil tempreture - where does one measure this ttemp

Where on a small block Chevy is the oil temperature measured? the C4 was the first Corvette I can think of with an oil temp readout, and I am certain the C5 has this feature as well. Is the temp taken in the oil pan or somewhere while the oil is under pressure and on the way to vital engine parts, or at the oil filter? Any information or facts appreciated and anxious to have your experience or input.

John,

C5 Oil temperature sensor is on engine block right beside oil filter.

Dave

[John M.]

Re: Oil tempreture - where does one measure this ttemp

On the oil pan lube temp, may we call that "expended oil" for the sake of clarity? It is oil that has been pressurized, worked its way through the lubrication system of the motor and removed heat from frictional surfaces and fallen back into the reserve for the oil pump. If that is an acceptable term, then what should we call the oil at the filter area as mentioned for the C5. Is it under pressure? Has it yet cooled anything? Has it passed through the oil filter yet? Is this where a factory oil cooler would get oil to cool or is there another source for the cooler and this tapped hole by the filter is the return for the cooler. To answer the question (what do you want to measure) the thing that I had in mind when posting this question is the measurement of lube temp as G.M. measured for the C4 and C5. I just have no idea where they choose to locate their probe. I am interested in the oil temp on a c2 but would like to use the same location as used on later cars so a comparative baseline could be established. Interested in your thoughts, advice, or experience.

[David H.]

Re: Oil tempreture - where does one measure this ttemp

John,

My guess, given sensor position on block next to oil filter, is sensor is in unfiltered (“dirty”) oil. C4 oil coolers went away with advent of Mobile One. Jim Lockwood’s earlier post (#2) seems more applicable to your situation i.e. in oil pan. In any case, your application would also have to use Mobile One to be comparable.

Dave

[Duke W.]

Re: Oil tempreture - where does one measure this ttemp

Assuming you don't have an oil cooler, the pan is the common place to measure. You can weld a bung low onto the side of the pan for the sensor, and I think you can also buy a drain plug that has a built in sensor with the spade for the wire connection.

If you have a cooler setup, it's a good idea to measure the temperature both into and out of the cooler, assuming it's after the pump, but on dry sump systems it's common for the scavenge pump(s) to route the oil to a cooler before it goes back into the supply tank. For a single sensor measure the output from the cooler, which is essentially the temperature going into the engine for either architecture, and you should have enough cooler heat transfer capacity to maintain it under about 230F except in the most extreme conditions.

A thermostat is also a good idea, too, so the oil heats up to operating temperature as fast as possible. I installed an oil cooler on my Cosworth Vega back in the early eighties before I started running track events. The oil routes to and from an adapter on the oil filter mount (and the filter is mounted to the adapter), which has a thermostat that begins to open at about 180 and is fully open at about 210.

Duke

[Jim D.]

Re: Oil tempreture - where does one measure this ttemp

For what it's worth, 1981 was the first year for an oil temp. gauge and the sending unit was installed just above the oil filter.

[John M.]

Re: Oil tempreture - where does one measure this ttemp

So here is what I am seeing: Put sensor on or in oil pan. A bung will be acceptable as well as use of a drain plug tapped for a sensor. Perhaps a digital sensor touching the outside surface of the oil pan would also read the temp of the oil inside? Your thoughts on this please. I assume the temp range would need to be from 100F. to 250F. to give results meaningful to engine operation. My observation has thus far been that engine oil temp is typically 20F higher than engine water temperature - is this a valid assumption for using oil in the pan for measuring temps? Are we all in general agreement thus far?

[Richard G.]

Re: Oil tempreture - where does one measure this ttemp

I agree with Duke, the pan is the easiest place for a retrofitted gauge. I had one in my 57 for years. A good blast onto the freeway could raise the oil temp 5 to 10 degrees. Of course it was delayed by a minute or about that as it took time for the oil to drain back and mix.

Years ago I read a story about the cars they run on the highway they close down in NV. They do high speed runs between two points. One fella had a 64 Chevelle and after his run he found a oil leak under the car in the staging area. Traced it to the nylon washer on the drain plug, it had melted away. After that he used a copper one.

[Jim L.]

Re: Oil tempreture - where does one measure this ttemp

Perhaps a digital sensor touching the outside surface of the oil pan would also read the temp of the oil inside?

On the outside of the pan the sensor could be subject to cooling from swirling ambient air. Can't prove it but I don't think you'd get an accurate reading.

I assume the temp range would need to be from 100F. to 250F. to give results meaningful to engine operation.

This is a good temperature range.

My observation has thus far been that engine oil temp is typically 20F higher than engine water temperature - is this a valid assumption for using oil in the pan for measuring temps?

What we've seen with my bride's track car, which sees occasional street driving, is that oil and water temps are virtually the same when the engine is just cruising at hiway speeds. On a sustained uphill pull, oil temp will rise above water temp. On the track, oil temps north of 230 are not uncommon while water temp remains around 180 - 190.

Hope this helps,
Jim

[Duke W.]

Re: Oil tempreture - where does one measure this ttemp

Does the track car have an oil cooler?

Duke

[Jim L.]

Re: Oil tempreture - where does one measure this ttemp

Does the track car have an oil cooler?

Duke

No, and I should have mentioned that.

My vintage racer does have an oil cooler and the oil temps never reach the levels seen on my bride's car. I can't cite oil temps in street use because the car isn't streetable.

[John M.]

Re: Oil tempreture - where does one measure this ttemp

Thanks to each of you for the help. Considering constructing a movable (car to car) set of probes to measure three of four temperatures - water, water leaving the radiator, oil, and ambient to be read on a digital readout panel, powered by the cigarette lighter plug. Also a volt meter included, and each function selected individually. Just something to gather accurate and meaningful information, as this type of info has always been of interest. The entire thing would be about the size of a smart phone but possibly twice as thick and powered by an Adrino (sp?) tiny computer. Writing programs and anything to do with this type of work is entirely unknown to me but may possible to figure out given enough time and effort. If successful or unsuccessful I will post the results here, and again, thanks for your input.

[Jim L.]

Re: Oil tempreture - where does one measure this ttemp

Arduino.

I suggest taking a course in "C" programming since the language for the Arduino is mostly "C"-like.

Definitely cute devices with capabilities limited only by your imagination.