Coolant Vs. Oil temps - what do you get?

For those with the capability to monitor both, I am curious as to what you are seeing?

 

I'd just like to get an idea of what people are seeing on our particular platform.

Nothing very interesting. They are simply correlated, just as the coolant and the ATF/CVTF can be if the radiator cooling circuit isn't bypassed (de-coupling the coolant temp from the ATF/CVTF temp).

 

You can easily monitor: Coolant Temp, Engine Oil Temp, Fuel Temp, ATF/CVTF Temp, Intake Air Temp, Ambient Temp and in some rare cases (or via a few equations) Charge Temp (Intake Manifold temp).

 

So long as each of these a. reach operating temp fairly quickly b. stay within reasonable ranges - there is no real reason to look at them aside from t00ning where temp compensations come into play.

Im moving towards monitoring but cant do it at this point in time

 

I am getting a feel for my coolant temps at various situations and hoping to roughly extrapolate oil temp. From here I can get a rough idea if I will do an oil cooler or not.

Skip an engine oil cooler, just do an ATF aux cooler (5EAT plumb guide on here)

ideally bypass the radiator for this. Install the STI thermostat.

 

 

 

Then revise your Radiator Fan mode settings in the t00n and call it a day.

 

 

Coolant and ATF will both run cooler, but not too cool.

Engine oil will also run cooler but still plenty warm like Subaru H4/6s like

and the fans will keep the engine bay properly vented. Done done

Perscitus, I appreciate you sharing the results of your experience.

 

Would you mind sharing how you came to these conclusions, and the data/experience behind it?

 

I'd love to understand the hows and whys behind things.

 

The fan mode settings I recall you posted info about in another thread, I'll look for it and read about it again some more.

Were you also referring to Climber's 5EAT cooler plumbing thread?

 

Came across that and IIRC he recommends keeping the coolqnt exchanger and plumbing the aux cooler before it, or using the thermostat to control flow to both coolers.

Yup that is the best (albeit somewhat complicated and more leak prone) solution.

 

 

No data handy anymore, just take my word for it.

 

 

I was done with data maybe 4 years ago. Now Im almost gone from this forum.

Why so? Shifting to a different platform? Burned out?

Why so? Shifting to a different platform? Burned out?

Because the grass is sometimes a little less brown on the other side of the fence.

 

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Skip an engine oil cooler, just do an ATF aux cooler (5EAT plumb guide on here)

ideally bypass the radiator for this.

 

I personally wouldn't recommend bypassing the radiator. I was told by transmission developer that transmission temperatures actually can get too cold.

Do as you decide and feel most comfortable. No vested interest here.

 

Bypass is perfect in lower 48, both for 4/5EAT and CVT/HVCVT. Better than stock setup in many ways. Too cold, sure, but its a function of a. fluid used b. driving habbits, c. ability or inability to monitor VB/pan temps.

 

With a good synthetic fluid anything above fluid temp of 30F is drivable, anything body tp and up safe, above 100 and up to 185 is goldylock zone.

 

 

 

Ran 5 cars this way for 20+ years, climate ambient temps up to 110F and down to -10F. Transmiasion fluid at drain n fills always perfect (OSAs, color, etc).

This is how a master transmission mechanic with 40yrs exp plumbs slushboxes.

 

 

 

Re grass, nah same s... different day. Maybe just a different type of grass.

 

After 9 years I needed a different flavor lol.

Because the grass is sometimes a little less brown on the other side of the fence.

 

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Wouldnt take much coming from where we are now.

I personally wouldn't recommend bypassing the radiator. I was told by transmission developer that transmission temperatures actually can get too cold.

 

I had heard that too and am interested to see all posibilities to choose the best from.

 

On my previous SG9 XT 4EAT I did plumb a B&M cooler after the rad cooler. It has since gotten tuned on a VF4i and is doing well so far with healthy looking fluid. Never did get to take temps so dont know if it is overcooled, but we are in the tropics and maybe that is why I got away with it.

Do as you decide and feel most comfortable. No vested interest here.

 

Bypass is perfect in lower 48, both for 4/5EAT and CVT/HVCVT. Better than stock setup in many ways. Too cold, sure, but its a function of a. fluid used b. driving habbits, c. ability or inability to monitor VB/pan temps.

 

With a good synthetic fluid anything above fluid temp of 30F is drivable, anything body tp and up safe, above 100 and up to 185 is goldylock zone.

 

 

 

Ran 5 cars this way for 20+ years, climate ambient temps up to 110F and down to -10F. Transmiasion fluid at drain n fills always perfect (OSAs, color, etc).

This is how a master transmission mechanic with 40yrs exp plumbs slushboxes.

 

 

 

Re grass, nah same s... different day. Maybe just a different type of grass.

 

After 9 years I needed a different flavor lol.

 

Maybe take a break, and get a Lexus? Working for some people.

 

Not really married to a particular direction at this point, learning as I go here. I realize I could plumb the cooler most any way or even just not touch anything and be perfectly fine, but where's the fun in that?

 

I see your point in decoupling, I see FI coolant temps have such a wide range that sometimes it might be best to decouple it from the trans. At full bore I see coolant temps going up and fast, just when you want to keep trans temps at operating. Being on a separate cooling circuit makes sense here.

 

I see climber was going in this direction by wanting to controling flow to the coolers via thermostat if possible.

 

Lots of ways to go about it and will be considering them all carefully.

Anyway I got my engine oil monitoring set up and been taking a look at coolant and oil temps.

 

Coolant temps are from OBD data. Oil temp and pressure from filter sandwich plate.

 

This is a JDM vehicle so no factory engine oil cooler.

 

Running Mobil 1 0w40 and OE Tokyo Roki filter, and I have an all aluminum radiator, STI 78c thermostat, and 50/50 Peak Global Lifetime coolant and distilled water.

 

At cold start, oil and coolant at ambient temp (20-30c), pressures are at mid 90's to a bit less than 100 psi.

 

Coolant temps were predictable at 85-95c or so. Warmed up, oil was at around 90-100c. Idle oil pressure warmed up is 17-20psi.

 

Hard driving I got oil above 100c to a peak of around 112c. Coolant would be about 95-105 at these temps, was not able to see exactly.

 

Still observing but what struck me is that at times coolant was at the 80s but oil temp could be up to 20c higher.

 

Also, I noticed that forcing the rad fan on by putting AC at full blast, I can bring coolant down to about 81c and oil to maybe 90c in 5-10 minutes. This is my cooldown procedure now.

 

With those oil temps I dont think I need an oil cooler just yet. And with the aluminum rad and STI thermostat, there is a lot of cooling capacity on the table so that setting the fans properly can probably bring average and peak temps down by quite a bit. Just like Perscitus said.

 

This is all kn the stock tune, will continue to drive around getting a baseline before installing the power mods and tuning.

I would be interested to see what the oil temps would drop to with an aux cooler...when I make up my mind which direction I am taking my car I will probably add some temp sensors as you have and an aux cooler for oil.

There is a lot of anecdotal info online, from Subaru owners who have fitted coolers. Sorry, cant remember off the top of my head at the moment how many degrees cooler they are getting.

 

I was planning to get a cooler on at the same time but after some research I decided to get sensors on first to see if a cooler is really needed.

 

Especially with you guys who have factory heat exchangers for engine oil.