Do I need an oil cooler?

[KillerBMotorsport]

Originally Posted by mike2100

I was reading a review of the 22 Subaru Forester Wilderness that states it has an air-to-oil cooler, which is one of the upgrades over standard Foresters that enables its 3000 lb tow rating (the other two upgrades being larger front brakes and a heavier duty transmission). Standard Forester tow rating is 1500 lbs.

I wonder how this oil cooler is designed, if it's anything like the 2nd gen GR86/BRZ water-to-oil cooler, and if it could be easily adapted to the FA24 engine.

It will likely be like any OEM remote coolers from Subaru have been like up to now, a small 2-pass loop. Better than the WTW setups, but by a small step. It will not be a substitute for a full-size performance unit.

[Westen86]

"For a dual-purpose car, engine oil needs to be at least 220 degrees F to burn off all the deposits and accumulated water vapor. For every pound of fuel burned in an engine, the combustion process also generates a pound of water! If engine sump temperatures rarely exceed 212 degrees (water's boiling point), the water will mix with sulfur (another combustion by-product) and create acids that can eventually damage bearings."

-Motor Trend acticle

Heat kills oil. Not time, not friction. Whats happening is a trade-off between heat deterioration and oil life. What you want is maximum protection for the amount of time between oil changes. Is 0w20 just fine for a race car? Yes, but for how long? Is 10w50 just fine for a race car? Yes, but for how long?

I dont think you are ever reaching a point with 10w50 where you are maximizing its capabilities. A thinner oil would protect your engine better GIVEN A STANDARD OIL CHANGE INTERVAL. Is 10w50 just fine for your car? Yes, but...


**this was meant for another thread. Still relevant I suppose.

[loungin]

Any updates on the topic? Do these cars actually have an oil temp sensor? Has anyone had a gen2 go into limp mode from oil temp?

After warming up, I hit 257 F in 4-5 laps at Thill East. Seems uncomfortable to me though I had switched out the oil to 5w20 after breakin.

I just want a cheap easy track car. I don’t want to get into mods but this plus the tire wear, tire choices, are making me think twice.

[JDMChris]

Originally Posted by loungin

Any updates on the topic? Do these cars actually have an oil temp sensor? Has anyone had a gen2 go into limp mode from oil temp?

After warming up, I hit 257 F in 4-5 laps at Thill East. Seems uncomfortable to me though I had switched out the oil to 5w20 after breakin.

I just want a cheap easy track car. I don’t want to get into mods but this plus the tire wear, tire choices, are making me think twice.

1st and 2nd Gen's get HOT. If you're tracking, it is best if you have an oil cooler. High oil temps reduce power, if it gets high enough, it can limp mode.

[eyeballs]

Originally Posted by loungin

I just want a cheap easy track car. I don’t want to get into mods but this plus the tire wear, tire choices, are making me think twice.

your answer is miata

[ZDan]

Originally Posted by loungin

Any updates on the topic? Do these cars actually have an oil temp sensor? Has anyone had a gen2 go into limp mode from oil temp?

After warming up, I hit 257 F in 4-5 laps at Thill East. Seems uncomfortable to me though I had switched out the oil to 5w20 after breakin.

I just want a cheap easy track car. I don’t want to get into mods but this plus the tire wear, tire choices, are making me think twice.

30-weigth synth would be a better choice than 5w20. 5w20 viscosity at higher oil temps is going to be about the same as 0w20 so not much point... I run 5w30 during track season in my '17 with no oil cooler(40+ track days, 74k street miles). I see max oil temps 270-275F at the track. This isn't a problem for any decent synthetic oil. Good 20-weight synth may be OK at 257F but I'd still go up to a 30-weight for track usage.

[zeroomega]

Originally Posted by loungin

Any updates on the topic? Do these cars actually have an oil temp sensor? Has anyone had a gen2 go into limp mode from oil temp?

After warming up, I hit 257 F in 4-5 laps at Thill East. Seems uncomfortable to me though I had switched out the oil to 5w20 after breakin.

I just want a cheap easy track car. I don’t want to get into mods but this plus the tire wear, tire choices, are making me think twice.

These cars have actual oil temp sensor, the temperature display in track mode is accurate (unless you have a BRZ which only display a bar). You can read the oil temperature data from the CAN bus. You probably won't get into limp mode even if push really hard (e.g. over 270F). But that doesn't mean it is alright for the engine. With oil heats up, pressure drops. I am seeing oil pressure drops to 45psi at 250F with oil cooler in a super hot day with my gen2. With 0w20 and oil heats up to 260F, that number could be dangerously low. We never know what is a minimal pressure these engine requires. I personally know a friend whose gen1 engine blown on the track with 5w30 oil and no oil cooler in a hot day at Sonoma. But it is hard to conclude that engine blown is caused by low oil pressure as he didn't do any data log at all. There is also a case on the GR86 Fb group that someone's GR86 spun a bearing with 0w20 oil and no oil cooler. But that one might due to other reasons, such as RTV. It is hard to tell. It only takes me 2 laps at my local tracks to heat my gen2 oil beyond 250F. So I got oil cooler right after my first track day with my gen2. Please do your own risk assessment and choose the best solution that works for you.

[x808drifter]

Originally Posted by eyeballs

your answer is miata

[ZDan]

Originally Posted by zeroomega

You probably won't get into limp mode even if push really hard (e.g. over 270F).

I never hit any factory "limp" mode in my gen1 at oil temps up to 275F.

But that doesn't mean it is alright for the engine. With oil heats up, pressure drops.

Which is why it's a good idea to run 30-weight (or higher) for track duty. Get the oil viscosity back in proper range for the operational temp.

I personally know a friend whose gen1 engine blown on the track with 5w30 oil and no oil cooler in a hot day at Sonoma.

I have a friend who lost his engine at Palmer this past June (mid 70s), *with* an oil cooler. Guess what he found on the oil pickup screen...

But it is hard to conclude that engine blown is caused by low oil pressure as he didn't do any data log at all. There is also a case on the GR86 Fb group that someone's GR86 spun a bearing with 0w20 oil and no oil cooler. But that one might due to other reasons, such as RTV.

Bingo... A quick search on the topic will show that *plenty* of these cars have lost engines due to poor oil delivery with oil coolers as well as without.

Regarding pressure, data shows that oil pressure is about the same for 5w30 at 250F *with* an oil cooler as it is for the same oil at 275F *without* a cooler, see 2nd chart post #1 here: https://www.ft86club.com/forums/showthread.php?t=91820
In this case, pressure drop due to the cooler was pretty much equal to pressure drop due to higher temps without the cooler.

For me, doing ~10-12 track days a year with ~10-15 minute sessions, I'm not worried about 270-275F oil temps running 5w30 synth with no cooler. IMO ensuring the oil pickup is clear before tracking might be considered a bigger priority than getting an oil cooler...

[Petah78]

Originally Posted by ZDan

I have a friend who lost his engine at Palmer this past June (mid 70s), *with* an oil cooler. Guess what he found on the oil pickup screen...

Gen1 car? I always suspected this RTV thing was a real concerns even for the FA20. MY in this specific case?

[OkieSnuffBox]

All modern cars run HOT on the track. Higher running temperatures = better thermal efficiency.

Originally Posted by eyeballs

your answer is miata

Maybe an NA/NB. The ND1/ND2, Flyin' Miata has developed an Engine Oil Cooler, transmission fluid cooler and differential fluid cooler because they run so hot.

Oh and they sell strong bolts for the transmission case to help keep them from flexing and breaking the I'm wanting to say 4th gear.

[OkieSnuffBox]

Originally Posted by zeroomega

You probably won't get into limp mode even if push really hard (e.g. over 270F). But that doesn't mean it is alright for the engine.

Most modern vehicles don't go into limp mode because of oil temp until they see 300F.

[ZDan]

Originally Posted by Petah78

Gen1 car? I always suspected this RTV thing was a real concerns even for the FA20. MY in this specific case?

Gen 1.2, 2017 like mine. The kicker is this car has seen similar track & street usage to mine, 73k street miles at time of failure. I'm at 74k... I had assumed that any issues were largely cleared up by 2015, certainly by 2017, but alas, apparently not the case. Also would have assumed that once past a relatively low number of track days and street mileage that failure rate would drop off to near-zero (bathtub curve), but again, not the case here!

I'ma drop my oil pan in the off-season and have a look...

[Petah78]

Originally Posted by ZDan

Gen 1.2, 2017 like mine. The kicker is this car has seen similar track & street usage to mine, 73k street miles at time of failure. I'm at 74k... I had assumed that any issues were largely cleared up by 2015, certainly by 2017, but alas, apparently not the case. Also would have assumed that once past a relatively low number of track days and street mileage that failure rate would drop off to near-zero (bathtub curve), but again, not the case here!

I'ma drop my oil pan in the off-season and have a look...

I wonder if the addition of an oil cooler reduced oil pressure to the point which caused more harm than good resulting in the failure.