DrMikeCSI
DrMikeCSI Reader
11/27/22 3:13 p.m.

I was watching the engine oil temp display om my Subaru Outback when I started driving to Cleveland this morning. This was all light throttle driving. The oil temp reached 180F after about 15 minutes and got to about 220F near the end of my trip. Interesting that driving uphill on the turnpike the temp went up to 222F and downhill it dropped to about 215F. This was going down into the Cuyahoga valley.  I would have thought that the oil temp would be stabile at that point. 

Mr_Asa
Mr_Asa UltimaDork
11/27/22 3:46 p.m.

Engine oil temp is gonna be a function of engine temp.  Going uphill you will be putting more of a load on the engine.  Going downhill, especially in cold weather, you are (kind of, but not really) idling and the engine gets a lot of cooling from the vehicle moving air across the radiator without any effort to the engine.

GameboyRMH
GameboyRMH MegaDork
11/27/22 3:53 p.m.

That all makes sense and sounds normal, especially for a car without an oil cooler. Higher engine load will cause oil temps to increase and if there's no cooler, it can rise to well above coolant temps, some engine designs don't have much heat transfer between the two and you can get a huge sustained difference in temperatures. 2.0L Toyobarus with no oil cooler can get oil temps close to 300F while the coolant temp is around 190-210F for example.

Generally full operating temp means a coolant temp in the 180-220F range and oil temps in the 190-230F range. Newer engines generally run hotter.

Edit: Also air-cooled engines and rotaries run even hotter than that. EV full operating temp is like 30-60C, anywhere close to ICE full operating temp would be a dangerous overheat for an EV.

codrus (Forum Supporter)
codrus (Forum Supporter) PowerDork
11/27/22 4:04 p.m.

Bah.  If you don't hit the rev limiter backing out of the garage, are you even trying? :)

 

1988RedT2
1988RedT2 MegaDork
11/27/22 5:23 p.m.

I've never been to the Cuyahoga valley, but if I ever get there, I'll be blasting this on the stereo:

 

DrMikeCSI
DrMikeCSI Reader
11/28/22 5:26 p.m.

Wow I can't believe I have never heard that before.  I lived here my entire life and I love the valley. 

1988RedT2
1988RedT2 MegaDork
11/29/22 11:46 a.m.
DrMikeCSI said:

Wow I can't believe I have never heard that before.  I lived here my entire life and I love the valley. 

One of my favorite REM songs ever.  Glad I was able to introduce it to you. angel

ShawnG
ShawnG MegaDork
11/29/22 12:51 p.m.

You car should be warm by now.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
11/29/22 7:15 p.m.

The local Quick Lube owes me lunch. Mongolian Beef with a side of vegetable fried rice pls. (Very few places do mapo tofu anymore and a lot of the ones that do, suck)

2017 530i, which of course has a 2 liter four cylinder. Their guy got the car's owner all freaking out because the coolant boiled over when they took the coolant reservoir cap off, and they said his thermostat was bad.

I drove the car.  Coolant temp stayed resolutely at 106-112C.  That is, if I get my furlongs to fortnights right, roughly 222-235F.  Seems high, right?

Thermostat opening temperature is about 105C, or 221F.  BMW wants that engine HOT for efficiency.

A 50/50 ethylene glycol coolant mix boils at 226F at atmospheric temperature.

 

So, nothing at all wrong with the car, and dingus who owes me lunch got someone freaking out over nothing.

 

Also, it idles at 92kpa manifold pressure (local atmospheric is 94-95) and the start/stop is very aggressive, it will shut the engine off while you are still rolling, braking to a stop!

obsolete
obsolete HalfDork
11/30/22 12:45 a.m.

In reply to Pete. (l33t FS) :

It idles with the throttle almost wide open? How?

Noddaz
Noddaz PowerDork
11/30/22 7:02 a.m.

I am surprised this took so long.

This is a bit too warmed up.  

GameboyRMH
GameboyRMH MegaDork
11/30/22 8:26 a.m.
obsolete said:

In reply to Pete. (l33t FS) :

It idles with the throttle almost wide open? How?

One of BMW's valve-lift-throttled engines I'd guess?

Fueled by Caffeine
Fueled by Caffeine MegaDork
11/30/22 8:30 a.m.

Never.  It's never warmed up. 
 

 

sincerly a Minnesotan. 

obsolete
obsolete HalfDork
11/30/22 11:05 a.m.

In reply to GameboyRMH :

Oh, this is a MultiAir-like situation. That makes sense, thanks.

 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
11/30/22 11:43 a.m.

In reply to obsolete :

BMW uses an actual camshaft to open the intake valves, but they have a variable geometry rocker/finger follower to allow the lift to be almost nothing.

Our Preferred Partners
tPbYWGV22jZGBp2Yv2amcILtwzMpOIcWKhhlUqfqiCZKEpYrArB3jT7AZXtHK11l