How hot is too hot for motor oil?

[A930Rocket]

How hot is too hot for motor oil?

I use 5W-30 full synthetic. Around town, it gets up to about 200* or so. At the track, it gets up to 240*. I have an external oil cooler mounted up front and a small fan but I have not installed it yet.

[John Rogers]

You have to figure where oil temperature is read at in the system. If the gauge is reading the sump temp then the engine block temp will have a big effect. I would suggest reading oil temps at external oil cooler inlet and outlet to see how well the oil cooler is working as your setup appears to not have a lot of air flow through the oil cooler so a temp drop should be good. I would also suggest moving the oil cooler further from the radiator which will require some trimming of the area in front of where the cooler sits and then see if there is a way to get the hot air vented out some how, maybe through the top meaning the hood will have to be cut and a Gurney Flap in front of the opening so there will be a low pressure area created to suck the hot air out. Good luck.
John

[pwd72s]

240 is too damned hot...just my opinion.

[Alan A]

https://www.syntheticoil.me/what-is-a-normal-engine-oil-temperature/

[A930Rocket]

The oil temperature sensor is in the bottom of the oil pan. Probably the hottest place, before it goes to the oil cooler?

There’s probably 4” between the oil cooler and the radiator.

I cut (4) 3” holes in the front bumper to get more air to the oil cooler and radiator. I can move it forward some, but I left enough room in front that I can fit a 6 inch fan, pushing air from the holes in the front bumper.

Maybe I move the oil cooler forward and use the fan as a puller?

If I duct the air from behind the oil cooler, it may block air going to the radiator.

I’d look for other places to put it using the fan, but haven’t found one yet.

[A930Rocket]

Originally Posted by Alan A

https://www.syntheticoil.me/what-is-a-normal-engine-oil-temperature/

A quick read of that link says that normal temps are 230 to 260* It needs to get over 212°, the burn off moisture. I change the oil before just about every track weekend.

[pwd72s]

My recollection is that I was told to not go past 220 on my old '72S gauge..that the thermostat setting was 180 for oil to flow to the front fender cooler.

[sc_rufctr]

There's no easy answer to this question.

IMO somewhere just above the boiling point of water (212°F) would be a good place to start... So 215°F - 220°F?

240°F (115°C) sounds too high.

[porsche tech]

They changed it on 911’s so you wouldn’t know how hot it was getting!

[KNS]

Cars today just seem to run hotter and as crazy as it sounds it’s considered “normal”. Modern BMWs run around 220-240+ but a lot of them have oil coolers too. We’d all freak at seeing these temps in our air cooled Porsches as Bruce Anderson would say it’s “too damn hot”

My 2019 VW has a 1.8 liter turbo four cylinder. It has an oil temp reading that can be displayed in the dash (not an idiot gauge). Typical is between 205 to 225. On hot days it runs into the 230s (hottest I’ve ever seen displayed is about 236). I run 5W-40 full syn and change every 5000 miles.

I think with you running an oil cooler and frequent oil changes before a track day you’re oaky (I have an E46 too). At the risk of starting an oil thread detour I would run a 5W-40 especially since you’re in South Carolina.

Edit: My 325i which I’ve owned since new has always run a 0W-40 or 5W-40. It’s lived most of its life in Phoenix, AZ (with the odd track day thrown in). At 245,000 miles I’ve only ever added a few ounces of oil between oil changes.

[rockfan4]

You've got a lot of air going in the front of the car, but where does it go? How does it get out from under the hood? Have you thought about venting the hood? Maybe not to this extreme, but a couple of vents.

[Jeff Higgins]

I remember when the C7 Corvette launched and one of the car mags did a track test at Willow Springs. Their oil temps got well over 280. Knowing that the car was equipped with an excessive oil temp shutoff system, wherein the car goes into "limp" mode to avoid damage, they researched just how high of an oil temp would trip that system. Turns out it is 315 degrees. So, in other words, Chevrolet appears to think that oil temps in the high 200's are "safe".

[john70t]

Hook up that external oil cooler/fan for track use and use heavier weight.

That OEM hood doesn't look like it provides enough flow through the grill.
It is made for DDing.

[A930Rocket]

Originally Posted by porsche tech

They changed it on 911’s so you wouldn’t know how hot it was getting!

With a flashlight, you could look under the gauge face edge and see a small hashmark, that was 212° if I recall correctly. Obviously, you can do that while driving, but if it you knew where it was, you had it, at least an idea of the temperature.

[A930Rocket]

Originally Posted by rockfan4

You've got a lot of air going in the front of the car, but where does it go? How does it get out from under the hood? Have you thought about venting the hood? Maybe not to this extreme, but a couple of vents.

Good point. I’ve been looking for some kind of louver I could retrofit to the hood. Something that would vent the air, but not let too much water in, if it rained.

[David]

My Cayman shows water temp and oil temp. Water temp always shows 194° but when I've driven around with the Durametric hooked up, it's all over the place. Oil temp seems to read accurately. On the track I was getting over 270° oil temp so I added the 3rd radiator up front and now it gets a little over 240°. All the more reason to change the oil before a track day.

[GH85Carrera]

Originally Posted by A930Rocket

A quick read of that link says that normal temps are 230 to 260* It needs to get over 212°, the burn off moisture. I change the oil before just about every track weekend.

Water, or moisture in any form does not need 212 to evaporate and "burn off" 185 will do just fine to get rid of moisture in the oil. Just pour water on the paved ground on a hot day and watch the water evaporate quickly.

My 85 911 will not go above 180 in cool temps outside. I can drive all day long in 40 degree temps and the oil temp will be 180 to 185.



Air cooled cars of course are mostly oil cooled cars. My gauge sits just above 180 in cool temps. When it gets hot outside, and the AC is cranked to max "keep Glen cool" it will climb to 210 to 215 and with the fan on the cooler running pretty much stay there and I have never seen it close to 250, even on the track and I really don't want to.

Of course the OP was talking about his water cooled engine. With water, it is easier to cool an engine. On my old El Camino, back when it was much newer and under 40,000 miles and 100% stock the water temp HOT idiot light would come on just driving it in on the highway. Even though my El Camino is a SS, (just a badge in the mid 80s) it came with no gauges but a speedometer and gas gauge. I swapped in a full stock gauge cluster about 30 years ago. The OEM 2 core radiator was just too small, and I put in a new 3 core radiator and now it will get to 220 in traffic and at long red lights, but it cools down to 200 in short order when moving. I like it at 190 to 210 for most efficiency.

To the OP, likely a bigger radiator is not an easy option for a BMW, unlike a G body GM vehicle with a endless list of suppliers. Fans and air flow is the only easy helper.

[pwd72s]

Glen's post above goes with my memory...if I'd ever seen 240 indicated on the gauge of my old 911S, I'd have freaked...

[cockerpunk]

Originally Posted by pwd72s

240 is too damned hot...just my opinion.

shouldnt be, 280-290 is where modern oils start to struggle.

[GH85Carrera]

The oil may start to struggle, but the heads gaskets, and different metal parts expanding at different rates are in trouble way before that. 250+ is bad news for most engines.