What's the highest safe temp the engine oil should reach during stop-and-go traffic and spirited driving?

 

i start to get nervous when i see 260 on my oil temp, i no it will take more but i back off when i get to 260+
john

 

I don't know about what is the max safe temp...
A sunthetic should be good to about 290....
But I use Roy,al Purple Purple Ice in my Dexcool and run a VaraRam.
The combination of cold air intake and surfactant in the rad leaves me at maximum 195 coolant and 220 oil.

 

I have seen over 300 on the track where there is a lot of WOT operation. Stop and Go temps are probably much lower even in 100 deg weather since the engine isn't producing much power and thus not producing much heat. I wouldn't worry unless it gets into the upper 200s. Your coolant shouldn't be over 230 (with AC on and the cooling fans running) and the oil temp is usually within 10 to 15 degrees of that when the car is running at slow speeds.
Bill

 

Thanks guys for the info and quick responses....

 

cruising im in the high 190's palying on the road it can go to 230. I havent seem it any hotter than 230

 

IMO there is no exact temp that you can say below is safe and above is not. As the temp increases, the oil's viscosity goes down. At a nominal oil temp of 212F, a 30 weight oil's viscosity is about 10-12 cSt. At 300F the typical 30 weight oil's viscosity is about 3 cSt. So while the synthetic won't break down immediately at that temp, it sure isn't providing the viscosity intended. To combat this loss of viscosity at these high temps, I have an oil cooler installed on my car. Additionally, if track temps are such that even with the cooler I see oil temps over 270F, I'll run AMSOIL Series 2000 20w50 which has a High Temp High Shear rating about 65% higher than the stock Mobil 1 5w30. If my oil temps are in the range of about 240-270F, I'll run AMSOIL SAE Synthetic High Performance 10w40 which has a High Temp High Shear rating about 39% higher than the stock Mobil 1. Note that neither of these oils meets GM Standard 4718M.

My personal comfort range for high rpm driving with a 30 weight is below 240F.

As for normal temps in stop and go traffic in hot weather, the oil temp will follow the coolant temp. On the high end, the coolant temp is controlled by the fans. Though the fan setpoints appear to have varied slightly over the years, they are about: low speed on at 226, off at 219; hi speed on at 235, off at 226. So in stop a go traffic, it is not abormal to see temps of 230 or so. Thus an oil temp in the 230s to 240s isn't abnormal either.

Other things to consider are that when the AC condensor is on, the fans will run, thus if it is hot enough out for the AC to run and the fans are on, but the load on the engine is low or airflow through the radiator is high, the temp will go down to the 194 range where the thermostat will go closed.

The car can reach an equilibrium in between 194 (thermostat closes) and 219 (fans come on) dependent on engine load and airflow/airtemp flowing through radiator, thus you see many guys say their car runs near 200-210.

 

Great info as usual

Don't the fans go off even if the AC is on when you get over a certain MPH ( I think 40mph)???


DH

 

As usual, Subdriver is Johnny-on-the-spot with the good info. Thanks...

 

Thanks Bounty.

Thanks Howie. I believe you are correct about a speed input, but I can't find a discussion about it in the service manual section on cooling. Maybe someone with LS1 Edit can confirm there is a setpoint for that.

 

DH is correct.....the speed input value is 35 mph. Above that the fans turn off unless activated by A/C.

 

Thanks Bounty, I'll add that to my file of all Vette knowledge.

 

have been sometimes checking oil temps on our c5; am surprised how frequently aligned it is w/ coolant temp. in fact, the coolant temp is typically just a few degrees cooler. bub

 

Since the C5 has no oil cooler, the coolant is the main heat removal source for the oil and the oil temp is generally going to hover a few degrees over the coolant temp as you have experienced.