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Minimum Oil Temperature?

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I installed an oil cooler with temperature and pressure gauges over the winter in anticipation of more track days this year. Everything worked great on my first couple of tests, but I'm now worried about it getting up to temp on cold mornings. I've seen plenty of discussion about maximum oil temperature but can't seem to find anything about minimum. What should I consider the coldest safe oil temperature before I start "beating" on it?

For context: My kit has a Setrab STD934 heat exchanger, Setrab oil filter spacer, Setrab oil filter thermostatic sandwich plate, and -12AN hoses. This got my total oil volume to about 10 quarts. My understanding of the thermostat in the sandwich plate is that it allows for the oil to bypass the exchanger when it's below 180°F; it doesn't force the oil to bypass, but rather to take the path of least resistance. It was a few weeks ago, but I finally had a chance to drive the car when it was a hair over 40°F outside. Luckily, there were no leaks but my oil temperature was much lower than I expected on the first drive. I did not have an oil temperature gauge before and was not sure what to expect.

I idled the car until my oil temp gauge moved from its resting position to the minimum mark at 140°F and the oil pressure dropped to just under 50psi; which took maybe 5 minutes. As soon as I took off, the temperature stayed at 140°F. After about 10 minutes of 35-60mph cruising the temperature did not move. I pulled over and felt the exchanger. The front face was a touch above ambient temperature, the back face was warm, and the hoses connecting the exchanger were somewhere in between. I then got on the highway and cruised at 75mph for another 10 minutes and the gauge didn't move until I exited and was waiting at a light, where it bumped up to maybe 145°F. I was a little bit more spirited when accelerating from stoplights (without beating on it) on the drive back to my house and it went right back to 140°F as soon as I got moving. It then went to 145°F after it idled in my garage before shutting off.

I'm sure that the really cold air did not help at all, and that 140°F is a lot better than anything below 100°F, but I'm not sure what I should consider a safe minimum operating temperature to be before I give it all of the beans. Our early and late season events in NE Ohio tend to be quite cold and it's not uncommon to see a high of 45°F. I'm worried that there might be a situation where we switch work groups and an Autocross quickly and it might not give my car much time to warm up, and I wouldn't want to beat on a cold engine. I'm debating on making a removable cover for the oil cooler heat exchangers for days like this.

As a disclaimer: I understand that I probably don't need an oil cooler for Autocross, even on warm days. I plan on attending more track days and a couple of Time Trial events.
 
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539
687
Exp. Type
Time Attack
Exp. Level
3-5 Years
SoCal
Following.
I'm nowhere near an expert but as I understand it, you shouldn't beat on the car until oil temps reach "operating temperature" - as per the all-knowing Google.
Now what exactly is "operating temp"? Well per the same refence, it's somewhere between 180°F and 220°F.

My other thought is that the intent is to burn off any water moisture that's made it's way into the oil, which water boils at 212°F so does that mean 212°F is your minimum full-throttle temp?
 
179
309
Utah
Being that I am old as dirt and a bit old school, I also use the pressure to tell me if the car is ready to go on track. If I get to grid and my idle pressure is in the 50 psi range, then I let it run/idle/rev a bit until idle psi gets down to about 35-40. My oil temp at that point is about 160-180, about the same as the coolant temp (depending on ambient temps). Coming off track the hot psi is about 25-30 at idle and the oil temps are north of 200 depending on the ambient temps.

The oil cooler will do your Coyote good no matter how you use it!
 
70
128
Exp. Type
Time Attack
Exp. Level
20+ Years
Melbourne Australia
Time to throw the cat amongst the pigeons, why are we concerned about oil being up to temperature?
Follow the train of thought and see if it makes any sense.

We are concerned about the "Engine" being up to temperature before, i know you lot, "thrashing the living crap out of it".
Understandably so, mechanical parts can be a bit fragile cold and have tolerances that are required when up to temperature.
We have no direct way of knowing what the metal parts temperature is. What therefore is our alternative. We have 2 fluid systems that circulate said engine, oil and water. One is for cooling, temperature related, and the other lubrication, we all know what happens when that fails.
Water reacts quicker to energy input than oil so will show temperature more aligned with the metal it is circulating through. Oil will get there but takes longer.
In this case then if the water temp has reached its operating temperature, or onto the scale and climbing given most start reading once within range, then so has the engine. Given all cars have an engine coolant temp gauge rather than an oil temperature gauge its the more appropriate measure.
Oil on the other hand is designed to operate as a lubricant across a wide range of temperatures, its the reason it has a normal rating and a winter rating. As mentioned previously its primary purpose is lubrication, yes it does act as a cooling fluid, once we add a cooler but its temperature is really an issue. Yes the pressure changes with temperature but aren't we all hunting higher rather than lower oil pressure. If we have pressure at start up then its doing its job already.
So in answer to the original question, if you drove to the track you have heat soak and you are good to go. If you trailered, how long does it take for your tyres to get some temperature into then. By then you have probably sat for a bit idling the car while getting strapped in. Queued up waiting in grid then headed out for a warm up lap to get some heat into those cold tyres. The only item that hasn't had a chance to get some heat into them and waiting to spit you off the track. Ask me how i know, have a whole series of photos with grass seeds on the spoiler.

Lets be honest, we all have a lot of money tied up in our hobby, irrespective of a quantified number, you still wont beat on it till you feel its right in your head.
Please by all means educate me if i am missing something from an engineering perspective. I'm here to learn like the rest of us.
 
1,249
1,243
In the V6L
There are three things that I've taken on board over the last 20 odd years of driving performance cars:

1. The engine oil temperature that matters the most is the oil temperature in the bearings that are being lubricated. Since you can't measure that directly, the next best thing is measuring the oil temperature in the sump, where the oil goes immediately after lubricating the bearings.

2. If you're not heading out onto a race track, then the best way to warm up the engine is to drive the car. For mine, when it might have been six weeks since the last time I drove it, I start it and let it run for about 30 seconds to make sure that there's oil in all the galleries. Then I start driving. I keep the revs down and the throttle light until I've got about 170 degrees EOT. The engine warms up faster when it's being used, and that matters a lot for things like the pistons and the other moving metal parts that have to expand into the spaces they have to work in. Getting the metal parts warm is as important, if not more important, than getting the oil up to temp.

3. If you are heading out onto a race track for the first time in the morning, there are four temperatures that matter: engine oil, gearbox oil, differential oil and tires. Fortunately, if you do one or maybe two 80% laps to warm up the tires, the rest of the important temperatures pretty much fall into line and you can move up to 100% without worrying about anything other than just getting on with the session..
 
Time to throw the cat amongst the pigeons, why are we concerned about oil being up to temperature?
Follow the train of thought and see if it makes any sense.

We are concerned about the "Engine" being up to temperature before, i know you lot, "thrashing the living crap out of it".
Understandably so, mechanical parts can be a bit fragile cold and have tolerances that are required when up to temperature.
We have no direct way of knowing what the metal parts temperature is. What therefore is our alternative. We have 2 fluid systems that circulate said engine, oil and water. One is for cooling, temperature related, and the other lubrication, we all know what happens when that fails.
Water reacts quicker to energy input than oil so will show temperature more aligned with the metal it is circulating through. Oil will get there but takes longer.
In this case then if the water temp has reached its operating temperature, or onto the scale and climbing given most start reading once within range, then so has the engine. Given all cars have an engine coolant temp gauge rather than an oil temperature gauge its the more appropriate measure.
Oil on the other hand is designed to operate as a lubricant across a wide range of temperatures, its the reason it has a normal rating and a winter rating. As mentioned previously its primary purpose is lubrication, yes it does act as a cooling fluid, once we add a cooler but its temperature is really an issue. Yes the pressure changes with temperature but aren't we all hunting higher rather than lower oil pressure. If we have pressure at start up then its doing its job already.
So in answer to the original question, if you drove to the track you have heat soak and you are good to go. If you trailered, how long does it take for your tyres to get some temperature into then. By then you have probably sat for a bit idling the car while getting strapped in. Queued up waiting in grid then headed out for a warm up lap to get some heat into those cold tyres. The only item that hasn't had a chance to get some heat into them and waiting to spit you off the track. Ask me how i know, have a whole series of photos with grass seeds on the spoiler.

Lets be honest, we all have a lot of money tied up in our hobby, irrespective of a quantified number, you still wont beat on it till you feel its right in your head.
Please by all means educate me if i am missing something from an engineering perspective. I'm here to learn like the rest of us.
You are on the right track, for the most part.

Yes, engine oil has a higher thermal capacity and will take more energy to heat up than the engine coolant. Another reason would be because the coolant is designed to cool around the cylinders from the heat produced during combustion and the engine oil, for the most part, is cooling and lubricating the rotating assembly where much less heat is naturally produced.

All metal parts in an engine will experience thermal expansion; as the name suggests, they will expand as they heat up. This modifies the tight clearances between vital components that the engine oil passes through. For example, the clearance between the crankshaft and the connecting rod bearings may be 0.0010" when cold but will be larger once up to temperature. The engine oil viscosity also changes with heat. Modern engine oil combines two different viscosities into one fluid. For example, 5W-50 acts like SAE 5-weight oil when cold but will act like SAE 50-weight oil when hot. While this does help to keep a more constant viscosity through a wider temperature range, the cold oil is still considerably less viscous (thicker) than it should be at operating temperatures. Both of these issues compound in severity in a cold engine and your oil pump is trying to force a thicker fluid through a smaller hole than designed. This is fine at low RPM, but could cause an issue at higher RPM if the oil is too thick to have sufficient flow through the too-small gap in the short amount of time that it has between rotations.

Heat Transfer and Fluid Mechanics were some of my least favorite engineering classes, but it's nice to see real-world examples of them.
 
Could it possibly be in the plate where oil returns from the cooler?
The temperature sender is in a separate adaptor plate that is before the sandwich plate. Below is a link to a similar setup that uses a spacer and sandwich plate like mine.
https://setrabusa.com/collections/s...filter-adapter-for-brz-fr-s-86-180ºf-t-stat-1

The oil flows out the engine block and then straight through the adaptor, where the temperature sender is. The oil then goes to the top of the sandwich plate, into a hose, through the exchanger, through the other hose, and then out the bottom of the sandwich plate and into the filter. The thermostatic bypass is open when the oil is cold and allows for it to take the path of least resistance, which should be straight through the sandwich plate and bypass the heat exchanger.
 
How’d you guys get AN12 fittings to fit on this? I’m looking at having to shave down one fitting considerably due to clearance issues on the sandwich plate.
Are you using the cast or billet part? The billet model is only sized for AN10 fittings. I called Setrab to confirm this, and the guy I talked to explained that the cast version is needed since the fittings are spaced further apart.

Here is a link to the one that I got. https://www.pegasusautoracing.com/productdetails.asp?RecID=28262
 
How’d you guys get AN12 fittings to fit on this? I’m looking at having to shave down one fitting considerably due to clearance issues on the sandwich plate.
I used the cast sandwiches adapter as mentioned above. I originally had the billet one when I used an10 lines but when I switched to the an12 lines I had to buy the cast adapter.
It take a bit of an effort but they do fit
 
IMG_7739.JPG

I don't know if this is much of an update, but here is a pic of the sandwich plate with the filter removed. It looks like the bypass is opening but the oil's path of least resistance is still through the exchanger. I have reached out to Setrab and they agreed that the temperature seems lower than it should be. I'll give an update once they get back to me.
 

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