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Is need of external oil cooler overblown
I have seen numerous videos saying the car needs an external oil cooler. I am not saying everyone is wrong.
My understanding is, which can certainly be wrong A good oil (5w30 oil with HTHS of 3.5+) should be able to protect well till 250-270F and a 0w40 beyond that till about 300F. I assume people see even higher temperatures than this and decide to get external oil cooler or few at lower temperatures. Then it seems to create it's own issue like pressure drop (I assume due to added space for oil) and it becomes a new problem where something like accusump is needed. And the whole system gets too complicated. Am I missing something 1. Are pressure drops are bad even on stock setup? Are there any numbers you could share? 2. Is there platform specific issue where oil can not protect engine like it does on European cars for similar temperatures (again probably related to oil pressure) Just trying to figure out why people start recommending oil cooler at 250°F. Again not saying they are wrong but what am I missing. Feel free to say I am wrong with reasoning if I am. |
This thread is often referenced
https://www.ft86club.com/forums/showthread.php?t=91820 Like you said, concern is not about oil breakdown. Rather, it's about proper pressure, which is an indicator of pumping effectiveness and oil flow. Pressure curves and data (both as a function of time over a lap and map versus temperature) are out there and especially concentrated in this forum. [ Google: oil pressure site:ft86club.com ] In the end, it's whatever condition you decide you're comfortable running the engine. Usually the breakover for people's comfort level hits around 260F. In practice, it's not hard at all to reach those kinds of oil temperatures on the track. It's usually not a concern for street driven cars, but it's still easy to raise temperatures to that level on a spirited high-rev drive on a curvy road Subaru thinks that 73psi (500 kPa) at 6k RPM is nominal for 176F (80C) oil temp; that works out to about 13psi per 1k RPM |
As said be Endless, pressure is what gets scary, there's just a correlation between temp and pressure that can necessitate a cooler
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Yes, hotter oil is thinner, that's why it is appropriate to run run 30- or 40-weight to have appropriate viscosity/thickness for higher oil temps seen while tracking. 5w30 at 275F is about the same viscosity as 0w20 at 250F. No big deal, oil temp "issue" is pretty overblown IMO...
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Thanks everyone. I understand high temperatures mean lower viscosity which results in lower pressure.
Oil cooler also reduces pressure at all temperature ranges. At 260°F the oil viscosity is 7.8 and 8.4 approximately for Pennzoil euro L 5w30 and Mobil1 FS 0w40, assuming oil cooler kept temperature at 212°F the viscosity would have been be 12.5 ans 13.8 instead. My question would be which is lower Oil pressure at 260 without external oil cooler Oil pressure at 212 with external oil cooler I understand at say 300°F as highest temperature without oil cooler, it would be better to have oil cooler and lower temperature. And at low temperature it would be worse to have oil cooler, pressure wise. What's the tipping point? 260°F? If so why? Sorry about lots of questions, just trying to understand and thanks everyone for reply. |
Not factoring in the drop on turns because it exists regardless of oil cooler.
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Attaching pic of graph showing the *same* oil pressure running 5w30 without an oil cooler at ~275F and with an oil cooler at ~250F, from this thread: https://www.ft86club.com/forums/showthread.php?t=91820 Quote:
If you're strictly worried about pressure, run 40-weight synthetic, it will give you higher pressure at 275F than 0w20 at probably 230F. Me, I usually run 5w30 Redline (HTHS 3.7) at the track, though I have also done track events with Subaru 0w20.... |
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Just for pressure argument sake, I looked at 300v 5w30 viscosity numbers and from that chart 240 is where pressure seems to be comfortably at what OP wanted (10psi/1000RPM), at 240F 300v should be about 8.11 cSt. Mobil1 FS 0W40 would have to be at 260F, and Pennzoil Euro L 5W30 would have to be at 250F for same viscosity. Both oils I have been interested in. 212F with oil cooler was a hypothetical best case scenario. By using same standards as above, with oil cooler temperatures would need to stay below 210F which seems is unlikely from your comment. So defeating the purpose of getting an oil cooler as oil cooler won't be able to compensate drop it caused. |
Larger coolers do not necessarily produce a large pressure drop:
Setrab Pro Line Series 1 coolers measure 8 1/4" long (6 7/16" not including mounting tabs) x 1 7/8" thick. The female M22x1.5 ports are 4.8" center-to-center. This 72 row size measures 22 1/8" tall (not including the hex on the port fittings). This is the largest Series 1 cooler available. It is recommended for use on engines making up to 600 hp. Expect a pressure drop of 1 psi or less with this cooler. @Ultramaroon has this one with a manual flow adjustment. I went with a series 1 Setrab 34 row cooler with the thermostatic sandwich. More and shorter rows results in less pressure drop. I respect what @ZDan says about not needing a cooler with quality higher viscosity oils but I'm not yet brave enough to go coolerless. |
230F-240F shouldn't be difficult to achieve with a good cooler on a NA car. Seeing as you have a 2nd gen the other thing you need to worry about is pressure drops due to G load at least that is what youtube says.
If it was me I would log the pressure you're seeing then post it here for some feedback. Maybe everything is fine and there is no need for any mods |
I run a Jackson racing dual cooler NA and my oil temps are 230ish steady.
I use Mobil 1 0W-40 |
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ETA I would have plucked the info regarding the cooler and oil temps and pressures from this forum. I don't recall if there was any pressure drop at all. |
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Just curious, have you done an oil analysis? |
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FWIW I ran 50 track days with my '17 BRZ PP, hitting upwards of 275F indicated at every single one of them. Usually ran 5w30 but also 0w20 for a few events. Never any issues. Friend's '17 with similar street/track miles as mine had his fail at Palmer MA last year, and he ran an oil cooler.
I think the indicated temperature is a calculated/adjusted value, not straight reporting from the sensor. I can't find it now but somewhere in these forums someone reported that 275F indicated corresponds to 255F measured sump temp. That's down to where you'd be ok with non-synthetic even (not that I would recommend it). Synthetics are good for sump temps up to at least 300F. Obsession with lower oil temperatures in these cars is IMO misguided. It would be one thing if high track oil temps correlated with failure rate, but as near as I can tell as many failed tracked engines have had oil coolers as not. I researched that obsessively for months before I bought my first BRZ in Dec. 2017 and then again after I started tracking it. No correlation between failures and cooler vs. no-cooler. |
Any information on why your friends motor failed ?
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https://www.ft86club.com/forums/showthread.php?t=153935 I had a huge drop as well. https://www.ft86club.com/forums/showthread.php?t=153186 |
Thanks for the links. I will be logging oil pressure for my next track day. Hopefully I don’t need to remove the oil cooler :( I won’t be buying the jr dual that’s for sure…
I have a first gen fyi so not sure how much of the info is the links apply. Either way it was a good read |
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IMHO: The oiling systems in the 2 engines are similar enough where the pressure drop due to cooler restrictions should be comparable. As I understand it, the issue with the Gen 2 is with right turns due to pan and pickup configuration. If you are comfortable with @ZDan's research, a cooler is a waste of time and money. |
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I’m more worried about pressure than temps. I will just see what the data shows after my next track day and go for there.
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It's cheaper and more beneficial to just drop the oil. I drop it every 2-3 track days. It's about $35 CDN without filter. It's not worth getting an analysis done. Yes, it could be overkill but it's cheap insurance. |
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Stock, coolant temps never get much above 200F
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Everybody "knows" you have to have a racing radiator and an oil cooler. The internet says so, so it must be true. |
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Another oil question.
Last weekend I ran at VIR. Ambient temps in the 70's. At 200*, I have 12-15psi/1000rpm. When my oil temperature was 220*-230*, my pressure stayed around 10psi/1000 rpm. 230* to 245* the pressure dropped to 6-8psi/1000. When temperatures bumped 250*, I had 40psi at 7000 rpm. I pulled into the paddock after that. I run Mobil 1 10w30. My oil temperature is measured at the spacer below the sandwich plate. Oil pressure is taken at the galley on top of the engine. Next event, I'm thinking of running Motul 5w40. Is there a better choice? |
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but yeah 55psi at 7k and near 70psi at normal street temps. Based off your data I would be getting myself a oil cooler but I think based off my location and normally only doing 5 Laps before pitting I can just keep the temps under 250F so no need in my situation. If you already have an oil cooler then IDK... YOLO it lol |
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Yes.
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How big is the core compared to say the JR racing one ? Also do you have a shroud |
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No shroud. It mounts to the back of the bash bar so it's only a couple of inches behind the grill. |
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I checked that the thermostat closes at 180*. So far, I can't figure out why my oil temps were so high. |
It can be tricky to get proper airflow. Cross flow between the coolers can actually kill the pressure differential needed to force air through. Might be as simple as walling off the area between the oil cooler and AC condenser. Try some cardboard and tape for science.
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The temperature problem only manifests on the track. In 2 weeks, I'm going to Summit Point. I'll wall off the open area and see what happens. |
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