What is considered as 'Optimal' engine oil temperature... ?

my vehicles have coolant-to-oil heat exchangers so i guess the oil is running near coolant temperatures. none of them have temperature sensors though id like to add them.
 
TiGeo said:
Always comedy folks trying to nitpick this funny comment. Clearly as a science-based activity NASA was using metric. Our county as a whole continues to use standard units and has accomplished more technologically than any other country on Earth which is the point of the joke...what's a kilometer anyway? 🤣
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Well that's easy and intuitive.... since 1 metre is the length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a second, 1 kilometer is the length of the path travelled by light in a vacuum during a time interval of 1000/299,792,458 of a second
 
Jetronic said:
Well that's easy and intuitive.... since 1 metre is the length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a second, 1 kilometer is the length of the path travelled by light in a vacuum during a time interval of 1000/299,792,458 of a second
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That makes WAY less sense than using the length of King Henry the First's shoe. 😁
 
mt23 said:
While this is generally true that many dont "get it" theres not a large difference, I may ask you what a large difference actually is? There are exceptions. My vehicle does not have an oil cooler and indicated steady state 75 degree ambient highway is 215 oil temp. 110 degrees ambient steady state highway oil temp may be 240. It was steady state 237 in 105 degrees ambient. 40 degree ambient steady state is around 205. All with coolant temps steady 194.
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It depends, of course. Looking at all the vehicles listed in your signature...which vehicle are you reporting on here? And, are you going by a readout or a calibrated temp sensor?
 
Titan said:
It depends, of course. Looking at all the vehicles listed in your signature...which vehicle are you reporting on here? And, are you going by a readout or a calibrated temp sensor?
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The 2018 Forester. No oil cooler, it has an oil temperature sensor readout which reports post oil pump and pre filter. Infrared thermometer on oil filter reports same temperature as the temperature sensor. I've seen as high as 255. The oil temperature is greatly influenced by outside air temperature and driving conditions. Give the engine a tailwind and it runs 10+ degrees hotter oil temp on highway in addition to outside temp influence. I would argue that there are probably many vehicles without oil coolers that are comparable in behavior. If talking kinematic viscosity there is a big difference between Grandmas short trip 180 degrees versus a more highway hot weather extreme of 250. Comparable to running 3 grades heavier oil in kinematic viscosity, for short tripping, 180 degrees versus 250 degrees.
 
BrendanC said:
my vehicles have coolant-to-oil heat exchangers so i guess the oil is running near coolant temperatures. none of them have temperature sensors though id like to add them.
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A good OBD2 reader may show your coolant temperature.
 
ZeeOSix said:
A good OBD2 reader may show your coolant temperature.
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i have a very nice scan tool, problem is none of my vehicles have any means to get an oil temperature. i’ve thought about a sandwhich plate on my silverado to get pre and post filter pressure and temperature down stream but with the coolant-to-oil exchanger in the radiator and HPL 5w-40 i just tend not to worry about it.
 
would a infra-red temp gun on the bottom of the oil pan work after running the engine a while then idle for 15 min. or so work?
 
My Jeep has direct readouts for both oil temperature, as well as trans temp. But no coolant temperature. It just has the typical "C----H", gauge with graduations. It stays fairly steady, regardless of ambient temperature.
 
billt460 said:
My Jeep has direct readouts for both oil temperature, as well as trans temp. But no coolant temperature. It just has the typical "C----H", gauge with graduations. It stays fairly steady, regardless of ambient temperature.
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Mine has all three digital - and they run highest to lowest:
Oil temp
Coolant temp
Trans temp
 
RDY4WAR said:
Are you saying that engineering teams always align optimal and acceptable without compromise? This isn't a perfect world. Many parts of a car are designed and built not out of optimization for longevity or functionality but rather comfort for the end user or because other factors take priority. The same applies to most everything. Nothing is without compromise. When it comes to oiling, factors like contamination and dilution headroom, pump cavitation prevention, fuel economy, etc... take priority over optimal oil temp. Your engine may cruise easy at a slightly less optimal 190°F oil temp, but OEM testing may have shown it can easily exceed 250°F or something with high load at low speed. They have to account for that while also keeping the warranty department happy and CAFE requirements met, plus other variables. A less than optimal oil temp on the highway is a small price to pay.
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The physical temp I posted is actually inside of the range you posted ...
 
Well I drive mostly Honda. I keep a 10mm wrench and socket just in case.

Cartridge pews are another thing. 9 short, 9 Kurz, 9x19,9x18,9x17, 7.65 Browning, 380etc. I don't know how people complicate things some much and yet the real madness comes not from those left clueless or in the dark but those that do have it covered.
 
Here is photo taken today. Eisenhower Tunnel, I70 Eastbound.
IMG_3284.jpeg
 
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OilUzer said:
What gear are you in and does the car have a small engine? RPM is kind of high so is the oil temp.
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5th, it shows M5, in manual mode.
Atlas, 2.0T. But I drive all my cars to the max. I spin it regularly up that hill to 6-6,500rpm. Atlas, Tiguan, BMW, or whatever I had previously.
Take into consideration it is almost at 11,000ft altitude. EVERY engine you push here will get hot, 3cyl or V12.
 
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