LethalTT

So i emailed these guys about the huge difference between the oil temps on the dash logic and the stock reading. The dash logic will read 230 just driving and my stock dash reading will say 215-217. They gave me some run around long winded answer instead of just answering my question of "Which one is more accurate?!! " maybe someone in here can tell which one I should pay attention to and maybe a quick reason why they are so different.

schpenxel

Dash logic uses estimated oil temp as this is all that is available over the CAN bus / OBD port

The reading on the dash is an actual reading from a temp sensor IF you have a temp sensor (Z51 cars do, I don't think base models do). If no sensor then the dash logic and dash reading should match as they would both be the estimated engine oil temp. This is calculated based on who knows what, but it isn't perfect.. thus the reason for the differences you're seeing.

The oil temp sensor is wired directly to the cluster, not through the ECM, so that info isn't available over the CAN bus / OBD

I assume this was easier than having a different harness going to the ECM depending on oil temp sensor or not? I'm not totally sure on the why.. I'm sure it was easier for someone to do it this way, despite the disadvantage that you've found.

Dan_the_C5_Man

Wait.. We might need to validate this.

I know I've read more than once that GM is presenting a "calculated" oil temp.

And I have carefully observed the delta, and my belief is that GM is "sandbagging" the oil temps to be lower than they actually are at the lower temps; when it hits a certain threshold it is more accurate to the real oil temp.

This bothered me to the point that I was going to buy a long thermometer to put in the oil tank to validate.

I can tell you that I only look at the Dashlogic display, could care less what it says on the DIC.

schpenxel

Well, the DIC is reality. Dash logic is using calculated, so the dic values are more accurate, assuming your car has an oil temp sensor.

Dan_the_C5_Man

I am not completely convinced. Maybe I will drop a digital temp probe into the tank, see what that says.

I just know that the temp reported by DL rises at a reasonable, predictable rate, and the DIC temp will sit there at lower levels forever, when engine run time and water temps would dictate otherwise..

And obviously the DL does not have a direct input from any sensor (except for a WB), I am suggesting manipulation from GM of the readout on the DIC.

If I do directly measure, I will post the results.

schpenxel

I would be interested in hearing what you find out. If you really wanted to get into it you could read the ohms of the wires coming off the sensor and probably find online what temp that equates to. Maybe anyways.

LethalTT

Thanks for inputs. So after many go around answers i got an answer which matches top post. From dash logic the performance models meaning Z51 GS Z06 ZR1 have more accurate oil temp sensor and we should use this over DL. Base models use same algorithm as the DL. So im pressing reset on my DIC to look at my oil temps and not using DL. I will maybe try to hit oil pan with my laser temp gun and see what she says but i think it will read hotter due to being on bottom of car. Thoughts?

Internets_Ninja

On my Z06 I have found that the DIC is correct and the DL is incorrect at lower oil temps. However when the temps come up to operating range the DL is pretty accurate. Not sure why but that is what I have observed.

Example, today I left my car parked for 2 hours after the oil was at full operating temp. When I started it back up the DIC said 145F and the DL said 180F. The DL continued to say 180F as the DIC climbed up to 185F. Then the DL read the same 185F. Weird.

I like the Dashlogic but its a little quirky.