How Hot Is Too Hot?

[Chuck]

Took our first long drive today. Water temp ran steady in the 180 - 190 degree range.

But oil temp ran 220 plus, cruising in 4th gear at 3500 RPM or 5th at 2500 RPM. We certainly were not pushing the engine. Air temp about 60 degrees. That seemed a bit high. Yet when we stopped, pulled out the dip stick and ran the oil through my fingers it was warm but not unreasonably hot. The engine did not seem to be overheated at all.

The sensor is located on the remote filter bracket.

I am guessing the oil temp just reads high.

The gauges are Classic Instruments.

Should this be cause for concern or a non issue?

 

[Randy V]

You're just fine Chuck.. I don't get concerned until the oil temp is above 250f and have run it as high as 300f on my racecars without damage but the Synthetic oil was changed and Oberg filter inspected (no trash in it) and the engine was run the rest of the season. It was 104 degrees and we were racing at Blackhawk Farms (swamp on two sides of the track) so the humidity was very high...

When we pulled it down at the end of the season it was fine just tired (rings and valves)..

 

[Jack Houpe]

I will let you know about oil temp in 3 weeks, I entered my car in the Big Bend Open Road Race in Texas. Its 59 miles one direction and then back again. I am dialed in at 110 mph which is the max for a first timer. I have had my car to 130 for about 2 minutes and seen the oil temp in the 240 range. Big Bend TX will be in the mid 80's outside temp so it will be a good test. I was wondering the same thing about Oil Temp and have concerns about it. I am running Mobil 1.

 

[Rick Muck- Mark IV]

Keep in mind oil temp should be over 212 to boil off any water. I had a hard time convincing that to the owner of P1116 as he thought it should be under 190. Under hard use 260-280 is not unreasonable with good quality oil.

 

[Andy Besic]

Is it possible that you header's were radiating heat to the sensor below? I couldn't tell from your second picture if the headers and collectors were in place. Mechanical temp lines also can be affected by running too close to heat sources.

Regarding the 220 temp. That is a great temp. I use 250 as a top with mineral based oils and 300 with racing synthetics.

 

[Chuck]

Thanks for the reassurance. We won't be concerned about 220 - 230 indicated temp.

What is odd, however, is that the oil in the pan on the dipstick is not that hot. At least according to the bare finger test . . . .

As I recall, the Classic gauge reads full scale when shorted and zero with resistance around 200 ohms One could easily add a 10 or 20 or 50 ohm resistor in series with the sensor and reduce the apparent reading on the scale a few degrees. But probably no point as long at it is a good relative indication rather than absolute indication of what is going on.

 

[Scott Calabro]

Shoot your trusty laser thermometer at the oil filter near the temp sender.....

 

[Chuck]

I will let you know about oil temp in 3 weeks, I entered my car in the Big Bend Open Road Race in Texas. Its 59 miles one direction and then back again. I am dialed in at 110 mph which is the max for a first timer. I have had my car to 130 for about 2 minutes and seen the oil temp in the 240 range. Big Bend TX will be in the mid 80's outside temp so it will be a good test. I was wondering the same thing about Oil Temp and have concerns about it. I am running Mobil 1.

Let us know how the race goes. Sounds like a good time.

We switched to Mobil I in the Cobra 427 after we turned over 3000 miles and have had no issues. Did not really seen any significant difference in either oil pressure or temp readings to speak of. We won't switch over to synthetics in the GT for at least a couple of thousand miles to give it time to break in.

 

[Chuck]

Shoot your trusty laser thermometer at the oil filter near the temp sender.....

Now why didn't I think of that!!!! Will give it a shot.

 

[Chuck]

Is it possible that you header's were radiating heat to the sensor below? I couldn't tell from your second picture if the headers and collectors were in place. Mechanical temp lines also can be affected by running too close to heat sources.

Regarding the 220 temp. That is a great temp. I use 250 as a top with mineral based oils and 300 with racing synthetics.

The sensor / filter / bracket is in free space remote from the headers. The oil lines run low and well below the headers. The sensor is electrical, not mechanical.