What's your idling oil temp?

[francesconyc]

I'm trying to investigate whether I'm overthinking my oil temp or not.
I live in Brooklyn, NYC. We have a 25mph and a lot of traffic lights, and I noticed that the majority of our users both here in US and Europe live in less dense areas where they can actually use the car "properly".

my oil temp stays lower whenever I can cruise more than a mile but
when I idle (or drive slow in traffic) for 30-40m my oil temp goes to 120 C, second white mark on style B gauge (220F using an infrared gun on the oil filter)
I'm already planning to add a fan on my fender radiator cooler. (carrera style but no fan at the moment)

but in the meantime what I'm asking here is just to understand if statistically, the car should stay cool also when idling or not

[Classic 911]

Interesting thread.


Sent from my iPhone using Tapatalk

[shoooo32]

So many variables. Ambient temp, elevation, driving style, 911 model, cooling upgrades, health of the cooling system (how many mice have been living under the shroud?!?), ignition timing, etc.

[spuggy]

Originally Posted by francesconyc

when I idle (or drive slow in traffic) for 30-40m my oil temp goes to 120 C, second white mark on style B gauge (220F using an infrared gun on the oil filter)

220F is getting up there (the external thermostat opens at, I believe, 185F or so, to direct oil to the front cooler(s)). So the system has more heat in it than the external lines and cooler can get rid of without airflow.

But 220F is just uncomfortably warm IMO, meaning keep an eye on it. 300F and over is when dino oils start breaking down and you should worry.

My 930, after 30 minutes of idling stationary (or near as makes no difference) in traffic will approach 240-250F on the oil temp gauge. Which will have me fast-idling it @ 2K RPM to get more air over the cylinders, heads and engine oil cooler (as this will knock 10-20F off the oil temps). Because a full-width FMOC does you no good at all with zero air flow through it...

If you fit a CHT and actually read the temperature during this, you'd be horrified at how hot the heads are getting after 10 minutes idling with no air flow from moving/minimal air flow from the fan in the back (because idling).

But many respected shops have an SOP of idling 911s to get the oil hot for a change - and they've been doing this for decades. I tend to think that if this actually caused problems, we'd probably know about it by now...

Originally Posted by francesconyc

I'm already planning to add an extra fan on my fender radiator cooler.

If I'm not mistaken (pretty sure), the stock factory temperature switch in the Carrera cooler doesn't switch the fan on until long after many think it should have. Like 250F or so.

Many fit a BMW switch that turns the fan on at a lower temperature, or an aftermarket one that engages at 200F...

low oil temp front oil cooler sensor p/n please

So you probably don't need to fit another fan, just use the one you have. You could probably also fit a manual switch in parallel with the thermoswitch to get in front of the temperatures earlier when stuck in traffic without replacing the thermoswitch.

[francesconyc]

Sorry i wanna clarify that my 82 SC has no fan at all. But at least i dont have a trombone so it will be easier to add a fan. Im also planning to keep it on when the car starts or maybe pass a manual switch in the cabin… will cross the bridge when i install it first.

Interesting answer btw. It seems your experience is not dissimilar to mine. Should i ride revving always at 2k and above ��… ?

[Duc Hunter]

My 89 Carrera tends to get warmer at ideal, and when you start to go 35 mph or over the temp comes. down. My 1975 with an RSR oil cooler up front, a 3.6 964 motor, and no engine mounted oil cooler tends to warm up a little on the freeway in the summer and at idle, and between 35mph-75 mph it runs cooler.

Oil heats up more slowly, and cools more slowly, than water will. I like to keep my oil temps below 250 for longer periods of time. If I’m in a drive through line and it gets warm I dont sweat it, or even heavy traffic. If it stays up there for 30 min or more I want to find some fresh air and cool her off.

[spuggy]

Originally Posted by francesconyc

Should i ride revving always at 2k and above ��… ?

Although it's called an "air-cooled", oil actually does a substantial portion of the work. But you need both - pretty sure you'd be sorry fairly quick if you ran the motor long without that big fan in the back.

The 930 & 3.2 engine fans are rated at 1500 liters/sec, and the SC only slightly less @ 1380 l/sec. Engine Fan Drive Ratio

None of them are moving anything vaguely resembling that amount of air at idle - and the oil pump is making minimal pressure/flow idling too.

If you're sitting stationary, there's no airflow over the fender oil cooler without a fan, or past the bottom of the motor. And because only a tiny fraction of the airflow from the big fan that would be pulling in cooler ambient air and pushing it under the shroud at higher RPM, the engine bay also tends to heat soak.

If I switch off for 10 minutes (eg stop for gas) with motor/oil up to operating temperature, I see IATs at the intercooler of 50C on re-start - which drop straight back to ambient after driving a block or two. And a 911 decklid has a much smaller grille/opening than a 930.

It's a sports car, with a basic design originating in the 1960's. They do a lot better when used as intended - eg moving - than sitting idling. Fit a thermo-controlled fan and check everything is working-as-designed and in good condition and don't worry about it overmuch. Or perhaps use a watercooled car if your primary use case is "mostly stopped" city driving.

[Discseven]

Dealt with similar problem---engine heating up to 250 at a long standing idle. Tested a few different things and ended up with a Mocal in the front right fender and adding 2 fans to it. Also added spray nozzles to the fans. Pump and water bag were in the frunk. Interesting to test but not something I wanted to maintain. Mounted switch for the fans in the dash. Constant driving, temp is 210 area. In stop and go traffic, it will rise and I switch on the fans and temp stays at 210. There's an air scoop Pelican and others sell that replaces one of the running lights. That scoop = waste of money.

Results from testing...

[AFB24911S]

My car (1977 911S with no front oil cooler, 11 blade fan) idles at 210°F in mild and cold weather (20°F to 60°F), but closer to 230°F above 60.

I'm having 3R Racing & Performance put an Elephant Racing single front fender oil cooler on it tomorrow, excited to see how much cooler it runs with that in hot weather and at the track.

[francesconyc]

Originally Posted by Discseven

Dealt with similar problem---engine heating up to 250 at a long standing idle. Tested a few different things and ended up with a Mocal in the front right fender and adding 2 fans to it. Also added spray nozzles to the fans. Pump and water bag were in the frunk. Interesting to test but not something I wanted to maintain. Mounted switch for the fans in the dash. Constant driving, temp is 210 area. In stop and go traffic, it will rise and I switch on the fans and temp stays at 210. There's an air scoop Pelican and others sell that replaces one of the running lights. That scoop = waste of money.

Results from testing...

Great diagram!
Well it seems my car is not abnormal then. I will def try to use it for longer rides for sure!

[Duc Hunter]

You could try to add a second fan to the fender cooler, so you go from zero to 2. The reality is that cooler does not get a ton of direct flow on the freeway. 2 good fans would help your situation a ton, and not hurt your highway cooling.

Also check the engine mounted cooler. As they get old they tend to get clogged with gunk, and no air can flow through them. A bit of a challenge to clean, but might be worth it. I know the CSF version has more capacity too, and it a bolt on. One of those is going on my Anniversary car and my rat rod soon, to help with teh hot Florida summers.

[GH85Carrera]

In Utah, on vacation I was stuck at a standstill for a construction project and a guy holding a stop sign until the oncoming traffic was done and we got to go. It was 100+ outside and my AC was cranked up. It got to 240 or so and I was about to turn the engine off and they let us go. It dropped to 210 in minutes.

That was the year I decided I really had to have a fan on my cooler. Last summer I drove to Palm Springs, CA for a week. On the trip home, I went to many cool sights. Joshua Tree park, the Very Large Array in New Mexico, down to Truth or Consequences, NM then to Alamogordo to the Space hall of fame and museum, up to Roswell and then towards home. There are areas out there that there is no one else around, and it was 100+ all the time.

I had the fan running and it never got above 220. If I turned off the fan, even driving at 80 MPH the oil temp would rise. So the fan stayed on. The AC blew 37 degree nice cold air a hurricane velocity, and I was cool.

[PeteKz]

My view: Oil temp should run in the range of 220*F. I know most of the time it's below that, but oils additive packages are designed to work best in that range, where it's hot enough to evaporate moisture out of the oil. I like to see 210-230. 240 is getting hot, and as Bruce Anderson wrote some years go, "250 is too damn hot." 190-200 doesn't get the moisture out of the oil effectively on shorter drives.

[917_Langheck]

The sun dries the pavement from a spring day rain, but it's nowhere near 190° at the ground when doing so. Condensation will evaporate when everything is at the same elevated temperature, even if below boiling point, and the vapor can escape to atmosphere. But, short drives don't usually result in even, elevated temperatures, so drive longer and have more fun.

[pampadori]

thinner oil will result in cooler oil temps compared to thicker oil
All things else constant, you'll have cooler temps with 10w40 than you will with 20W50.

You could I suppose consider that if you want lower oil temp. This will impact your oil pressure as well though.

[francesconyc]

interesting facts. im not sure which oil I have now. next change maybe I can do a 10-40 or maybe the Porsche 10-50?

[darrin]

Francesco -- if you don't know what oil you're running (or how many miles that oil/filter have been in your engine), an oil change might be a great next step. I've run 15w/50 mobil one oil in my Carrera for a while and have been happy with its hot weather performance in my '86 Carrera (which still lacks an oil cooler fan), but as Pampadori indicated, it would be interesting to see whether going with a thinner oil (10w40 vs 15w50 or 10w50) would result in any change to your traffic jam situation. Note that there are a lot of opinions regarding what constitutes the "best" oil for our cars.

[francesconyc]

I only know the PO changed it recently, less than 1,000 miles ago, but yes, I can def change it. also I think PO overfilled it a bit.

for now, I'm lucky that I have no oil leaks and I'd love to keep it that way. so I would avoid full synth, I was looking at semi-synth LiquiMoly sold on Pelican... my car is 1982 SC

[francesconyc]

this (i just realized is synthetic!)
https://www.pelicanparts.com/More_Info/2043.htm?pn=2043-M792&SVSVSI=911M

or
https://www.pelicanparts.com/More_Info/2043.htm?pn=2043-M792&SVSVSI=911M

[PeteKz]

Originally Posted by 917_Langheck

The sun dries the pavement from a spring day rain, but it's nowhere near 190° at the ground when doing so. Condensation will evaporate when everything is at the same elevated temperature, even if below boiling point, and the vapor can escape to atmosphere. But, short drives don't usually result in even, elevated temperatures, so drive longer and have more fun.

I definitely agree on driving it longer!