Teach me about oil coolers

I'm always planning, and I think my next mod will be an oil cooler. The STI is becoming more of a track/fun car, and I've noticed my oil temps can get quite high at the track during the summer. I haven't started my research, but I was hoping some of you could point me in the right direction, or tell me some things to keep in mind. I guess I know enough to know that mounting location can be important, both for where you get/return the oil (eg sandwich adapter with the filter) and for the cooler itself. I also know there are bar & plate and tube & fin...i don't know much about the difference. I also assume there are setups with thermostats, different sizes, etc... and I'm hoping people can help me get off on the right foot.

Ok, just began my research.

It seems like Setrab is an established brand, so right now I'm leaning towards them. I saw [MENTION=9]HolyCrapItsFast[/MENTION] has the Derale one, so I'll investigate a bit more. I'm not sure I need the crazy fans though, do I?

But now I'm wondering about size. 13 row? 16? etc...

And I'm thinking about mounting and locations. Do i need shrouds, or just throw it up there.

http://www.licmotorsports.com/products/csf-radiatoroil-cooler-combo-02-07-wrxsti_csf-3076o Another interesting option. Stock radiators are often replaced (failure? inadequate?), right? Do you think this could really be a "two birds, one stone" type of thing? It seems downright affordable for the price of a radiator setup and a thermostatic oil cooler setup.

i find it funny that you are having a conversation with yourself lol.. i dont know much about oil coolers but i feel like it wouldnt be that great of an idea to have the oil and coolant running that close to each other through a single radiator/cooler. radiators do get replaced its just one of those things that is needed i recently did one on my 07 and i got a mishimoto and its been great so far.. my opinion would be to keep them separate. idk if it explains what is keeping them separate inside that one radiator and what the possibilities are of it failing and mixing

Some key points I have found while using my oil cooler and doing research on oil coolers in general. Also the optimal oil temperature is essential. Otherwise you get significant swings in oil viscosity as temperatures climb. To thin and you risk spinning bearings because the shear properties of the oil has broken down and it becomes more compressible. To thick and the flow is not sufficient enough to lubricate and remove heat from the bearings. Ideal temperature is between 180 and 195 degrees for most oils.

Key point 1. is Air flow through the oil cooler. Nothing is more important. Most of the oil coolers on the market are adequate, but most applications fall short on air flow and even the most efficient coolers can fail at their job. I have found that just placing the oil cooler near an open duct is not enough especially when the car is still in traffic or driving at low speeds. You almost certainly want some kind of fan. A simple thermostatic switch place on the outlet side of the oil cooler will be sufficient enough to control the fans. I would go one step further and attach a switch to activate the fans during very hard driving.

Key point 2. Line size and length. I recommend a -10AN size line or larger which is large enough to allow sufficient flow. Also the length of the line should be as short a run as possible to reduce the effects of pressure drop. With shorter lines there is also less old oil left in the system when changing oil.

Key point 3. Consider bypassing the existing oil cooler/heater and remove it completely. This only serves to heat the oil to the same temperature as the coolant before it reaches the oil cooler and that can make more work for the oil cooler to do. The coolant temps can easily go beyond 212 degrees which is too high an oil temperature for my taste. Think about this though because the existing system also acts to get the oil temp up to operating temperature quickly. Also in other cases the existing oil cooler can act as a pre-cooler during very hard driving conditions. In my circumstance, I chose to eliminate it all together because I have a thermostatic sandwich plate that bypasses the oil cooler while the car is warming up and then diverts it to the cooler when it reaches 180*. I then use a complex controller to regulate temperature to a range precisely between 185* and 190* from then on

With my current setup, My oil temps reach operating temperature fairly quickly and the temp is very well regulated with the fans. I could easily make you a module to control activation of a fans. And I do recommend you consider Derale. Just from simple trial I can say the product is as good as they say. Once the fans kick on the temp falls from 190* to 185* in less than 20 seconds in the most brutal of hot days and the hardest driving conditions.

War_Panda04 said:

i find it funny that you are having a conversation with yourself lol.. i dont know much about oil coolers but i feel like it wouldnt be that great of an idea to have the oil and coolant running that close to each other through a single radiator/cooler. radiators do get replaced its just one of those things that is needed i recently did one on my 07 and i got a mishimoto and its been great so far.. my opinion would be to keep them separate. idk if it explains what is keeping them separate inside that one radiator and what the possibilities are of it failing and mixing

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Not to mention the the existing oil cooler does exactly the same thing. It is cooled by the engine coolant. So no need to run the oil to the radiator.

Also with the fans you can place the cooler anywhere you want with out worrying about shrouds and ducts. Just make sure that if you mount it near any other radiator, that you make it the first one to see air flow.

So you think the Derale fanned version would have equivalent performance to a front-mounted version at the track. I know that the oil cooler COULD see wind of 140+ mph, but as you mentioned, I don't know how much actually goes through vs around.

Dunno where I'd mount the fanned (Derale) version. How thick is it?

nice write up [MENTION=9]HolyCrapItsFast[/MENTION] i live in New York and it doesn't get extremely hot here maybe just breaking 100 degrees on a bad day. would you suggest still running an aftermarket oil cooler? im not gunna like i get on the car a bit i enjoy my driving lol

Grinder34 said:

So you think the Derale fanned version would have equivalent performance to a front-mounted version at the track. I know that the oil cooler COULD see wind of 140+ mph, but as you mentioned, I don't know how much actually goes through vs around.

Dunno where I'd mount the fanned (Derale) version. How thick is it?

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The total dimensions from fan back to front face is about 5" deep. total length is around 10-12 inches and it is about 7" tall. I'm sure they have dimensions somewhere on their site. The unit has a shroud and the fans are quite efficient at pulling air through no matter what the outside conditions are. They are more than sufficient for the application and they maintain the oil at temperature which is more than I can hope. I am not saying that the fans are better flow than a front mounted system, but that they are very consistent no matter what the outside influences are.

With a fan setup you can mount the unit anywhere your heart desires as long as the chamber it is in has air flow in and out to allow replenishment of the circulating air. If you do front mount it, I would still use fans just because of low speed and stopped conditions. Your oil is heating up on the line while staged for a race and that to me is a critical time for oil to be at the right temperature. Take-off and launch are very hard conditions for the car to see.

War_Panda04 said:

nice write up @HolyCrapItsFast i live in New York and it doesn't get extremely hot here maybe just breaking 100 degrees on a bad day. would you suggest still running an aftermarket oil cooler? im not gunna like i get on the car a bit i enjoy my driving lol

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If you are not running an HPDE event then I would say it is a luxury. An oil cooler is really recommended for prolonged hard driving and any high reving situation. The only reason I did it was for the purpose of gaining some real world knowledge plus I personally think the oil gets to hot in our cars. I would take long trips down south and cringe the whole way knowing how hot my oil was getting. If you use a good quality oil like AmsOil, Then there is little to worry about for your driving habits IMO

You would also be surprised at how fast your oil temps climb when you get on it. I mean literally seconds. Outside temperature has little effect on oil temperature when the engine is at operating temperature so no matter what your climate is, it will likely have little effect. The oil pan itself does allot to sink heat away from the oil so that would be the only part exposed to the elements to allow it to cool more in colder climates.

gottcha.. good to know thanks man

HolyCrapItsFast said:

The total dimensions from fan back to front face is about 5" deep. total length is around 10-12 inches and it is about 7" tall. I'm sure they have dimensions somewhere on their site. The unit has a shroud and the fans are quite efficient at pulling air through no matter what the outside conditions are. They are more than sufficient for the application and they maintain the oil at temperature which is more than I can hope. I am not saying that the fans are better flow than a front mounted system, but that they are very consistent no matter what the outside influences are.

With a fan setup you can mount the unit anywhere your heart desires as long as the chamber it is in has air flow in and out to allow replenishment of the circulating air. If you do front mount it, I would still use fans just because of low speed and stopped conditions. Your oil is heating up on the line while staged for a race and that to me is a critical time for oil to be at the right temperature. Take-off and launch are very hard conditions for the car to see.

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You did something fancy with your controller, but how do the fans normally turn on? Is it an internal thermostat?
I'm trying to think of anywhere big enough for a package that size, and there aren't many places! I'm using my fog lights as brake duct inlets. Maybe I'll have to hack together a cardboard box and see if there's anywhere good for it to fit. At 5" deep, I think it'd be hard to front mount it and have it look somewhat discreet. But since I'm not running an FMIC, i guess it's doable, as some of those are pretty thick!

i have also seen on a car running a FMIC they make a mount (i think SMY performance sells it) to put the oil cooler where the TMIC would be

google "top mount oil cooler" on images it comes right up. plenty of air flow but you would need a FMIC

A little hard to see in the pics but this is SMY's shop car



Bottom left corner




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Found better ones on his personal page.






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Grinder34 said:

You did something fancy with your controller, but how do the fans normally turn on? Is it an internal thermostat?
I'm trying to think of anywhere big enough for a package that size, and there aren't many places! I'm using my fog lights as brake duct inlets. Maybe I'll have to hack together a cardboard box and see if there's anywhere good for it to fit. At 5" deep, I think it'd be hard to front mount it and have it look somewhat discreet. But since I'm not running an FMIC, i guess it's doable, as some of those are pretty thick!

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A simple thermostatic switch on the outlet side of the cooler will do. Also if it is a matter is making you a controller I will... for free. It is nothing for me to do that.

I also had issues trying to find a good place for the cooler. I happened by my current location by happenstance only. It was a lucky day.

HolyCrapItsFast said:

If you are not running an HPDE event then I would say it is a luxury. An oil cooler is really recommended for prolonged hard driving and any high reving situation. The only reason I did it was for the purpose of gaining some real world knowledge plus I personally think the oil gets to hot in our cars. I would take long trips down south and cringe the whole way knowing how hot my oil was getting. If you use a good quality oil like AmsOil, Then there is little to worry about for your driving habits IMO

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Ditto. I have yet to figure out what the "optimal" oil temp is, but Ive heard anywhere from 180-220. I can easily get north of 210 around town in anything but the winter.

But on track days I'd see the oil going north of 240 (I may have seen 260+...its been a while now). And that was on a light-jacket day in May. The oil was getting WAY too hot, and if I were to do it in the summer, things would just be that much worse.

Grinder34 said:

Ditto. I have yet to figure out what the "optimal" oil temp is, but Ive heard anywhere from 180-220. I can easily get north of 210 around town in anything but the winter.

But on track days I'd see the oil going north of 240 (I may have seen 260+...its been a while now). And that was on a light-jacket day in May. The oil was getting WAY too hot, and if I were to do it in the summer, things would just be that much worse.

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I think 220 is my personal limit. For conventional oils and group III synthetic "if you can call it synthetic" then 180-200 is the optimal range. Group 4 and 5 have a much wider range but I still wouldn't go that high. Also build clearances and tolerances are a factor but I just don't know or care about the dynamics involved with that.