Hot Engine Oil Problem - Need some ideas

[RT-BRZ]

This is probably going to be a long one.

Car config:

2013 Subaru BRZ
-Stock FA20
-Killerbee oil pickup and a baffle
-Koyorad radiator
-JDL low profile shroud with the big fans
-Mishimoto 19 row oil cooler with thermostatic sandwich plate (the kit they sell)
-Link ECU G5 GT86 with Link wideband controller and sensor
-JDL v2.1 turbo kit - Garrett GTX2860R Gen2 with external dump WG, UEL header, 3" down pipe, standard intercooler, all other piping coated
-MotoEast Flex Fuel system controlled by the Link ECU
-Mostly other standard stuff except a lot of suspension updates.
-The car has ~30,000 miles on it. It's only been used to race in things like autocross for most of it's life. The oil has been changed many, many times in the last 5 years I've had it because of the upgrades and racing. The oil has never come out dark because of that.

Back story.
Prior to this situation, the car ran great. I raced it in autocross the weekend of June 29th and had no issues at the event or on the way home.

About a week and a half ago, I changed the oil from Motul 5w30 to Motul 5w40. I did the usual overfill but I think I went a little over that because I was probably about 1.5 quarts over rather than 1 quart over. Last Saturday, I drove the car over to get it washed at the local car wash (power washer only). I finished the wash and drove the car home. The drive is about 10 miles and half is on the highway. The car ran fine the entire way and I was running with the AC on. As I was coming up a small hill with a 4 way stop at the top, the car died when I pushed in the clutch. As I restarted the car, I looked down at my aftermarket gauges and noticed that the oil temp gauge was pegged at 300F. I was obviously a little panicked but was only about a mile from home so I drove the car home at very low RPM. During this time I had somewhat normal oil pressure (a little low because it was hot) but it was within the 10psi per 1000rpm range). I got the car home and parked it to let it cool off. About an hour and a half later, I used my oil extractor and pulled the extra 1.5 quarts out. I let the car sit until Sunday. On Sunday, thinking I had the problem fixed, I went to drive it to an event locally. Within ~5 miles, the oil temps were at about 280F and still climbing. I turned around and took the car home driving at low RPM. Effectively, this is the baseline of the issue.

• Sunday night, I changed the oil again. I took out the 5w40 and replaced it with fresh 5w40 Motul. Looked at the oil to make sure no metal flakes and it was clean. I did this to make sure the oil didn't get damaged by the heat. Yeah, I know, dumb.

• Tested Monday morning, no change.

• Wondering if the thermostat was stuck, I pulled out the thermostatic plate and put in the non-thermostatic plate. Tested, no change.

• Finding nothing that made sense, I ordered 5w30 oil to change it. In the mean time, I emptied the catch can which was fairly full but I'd never emptied before. I also pulled and cleaned the PCV. No change.

• Changed the oil. No metal in the oil. It was clean. Cut open the filter. No metal, it was clean. No change. (duh)

• Connected to the Link to make sure nothing was wrong there, realized that LAMBDA was reporting because of a config error. Fixed it. BTW, this just means I was running Open Loop vs Closed Loop and my tuner had it so close that LAMBDA is only making 1-3% fuel changes. So, not lean ever.

• Tested this morning. Same issue.

The car runs absolutely fine other than the oil getting hot. I'm unclear what the next steps to troubleshoot could be.

Also, if you throw out an idea, I'm going to process it logically. I'm not trying to argue with anyone. I'm just trying to make it all make sense. I've had it suggested that the overfill may have clogged something in the oil or PCV system but I don't really know how to troubleshoot something like that. I'm not having any major oil pressure drops or anything other than high oil temps. I'm stumped.

[Ohio Enthusiast]

What's the coolant temp like?
How are you measuring oil temp? Stock sensor? Aftermarket sensor? Might be a bad sensor.
300 seems extremely high for these cars. Before my oil cooler on stock unmodified NA engine I never saw above 270 on track. I would expect a turbo setup to run hotter but not at normal street driving.

[smackrel]

Is there a limiter, pressure or otherwise to cut flow to the turbo?

More oil flow thru the turbo causing it to heat up more than normal?

[RT-BRZ]

Originally Posted by Ohio Enthusiast

What's the coolant temp like?
How are you measuring oil temp? Stock sensor? Aftermarket sensor? Might be a bad sensor.
300 seems extremely high for these cars. Before my oil cooler on stock unmodified NA engine I never saw above 270 on track. I would expect a turbo setup to run hotter but not at normal street driving.

Coolant temps are normal they top out at like 217F but that's when the oil is like 280F. Sorry, I forgot to mention that.

Also forgot to mention, I have the OEM sensor that I'm pulling data from with RaceCapture and I have an add-in oil temp gauge and they match. I also used a pyrometer to test the temps of the oil filter sandwich plate, the add-in sensor and the OEM sensor and they are all within a few degrees of each other. Everything at the filter housing lines up with the temps I'm seeing.

Yeah, I really hoped it was just a bad sensor.

[RT-BRZ]

Originally Posted by smackrel

Is there a limiter, pressure or otherwise to cut flow to the turbo?

More oil flow thru the turbo causing it to heat up more than normal?

This is the standard JDL kit and there is a restrictor on the turbo side for the oil supply line but that's standard. It has worked just fine for the last several months so I wouldn't expect it to suddenly change.

However, I also measured temps at the exit side of the turbo/downpipe, the turbo center section and the cool side with the pyrometer and all of the temps were exactly where they always were. This turbo has a coolant loop through it and it matches what the coolant temp sensor shows.

[RT-BRZ]

You guys are never going to believe this. I think I found the issue. The lower coolant hose had popped off the car and it had no coolant at all.

I am still completely stumped by how this didn't kill the engine. OMFG

[smackrel]

Originally Posted by RT-BRZ

You guys are never going to believe this. I think I found the issue. The lower coolant hose had popped off the car and it had no coolant at all.

I am still completely stumped by how this didn't kill the engine. OMFG

Holy. Fuck.

How it didn't kill the engine is one thing, but how did you not notice is the question I need answered lol

[RT-BRZ]

Originally Posted by smackrel

Holy. Fuck.

How it didn't kill the engine is one thing, but how did you not notice is the question I need answered lol

The forums have been down for the last couple of days so I couldn't post any updates.

Looks like there is damage unfortunately. While the car does seem to run just fine, it's looking like I have either a blown head gasket or something warped/cracked. During heavier loads, the cooling system heats up to 220F-230F. It does cool down when you get back off of it but it led to me suspecting the issue. I got a coolant test kit for combustion gases in the coolant and here's what I got.

I will try to do a leak down test but the car is shut down for the season and I'll figure out what I want to do next.

[smackrel]

Fudgesicle. Sorry to hear it man