Normalized Oil Temperature vs Grade Selection

[HangerHarley]

This is somewhat in line with the Thermostat question posted by someone else, but recently a good point was brought up as to "Normalized Oil Temperature." I can only think that "Normal" Oil Temperature is between 200 and 240 Degrees in most engines. Was the Comment on some days past Thread regarding "Plenty of Engines not running at Normalized Oil Temperature with Oil Way too Thick" made to explain the formation of Sludge? Or, that Oil must be the correct Grade to the Temperature of the Engine?

Or is this a case of the Temperature will be the same, regardless the Grade, so it is selected Otherwise? -30? -40? -50? And im still amazed at the -20 choices (Logic being 30 turns into a 20, 50 turns into a 40, etc at Temp, "Shears") - ? so "20" does not Shear to a "10?"

This concept of "Normalized Oil Temperature" Intrigues me, as it relates to Selection of Oil, specifically Grade, not so much "Synthetic" or Base Stock selection.

Any Info along this subject of Oil Temperature vs Oil?

 

[Gary Allan]

I'd put it at 180F/190F-220F. I'm pretty sure that would work for more people than it would not. On common usage there's limits to what you'll reach as long as the cooling system has ample reserve capacity. Oil temp tends to be the unthrottled and unregulated excess of heat exiting the engine that isn't going out through the rad or the exhaust. As load increases, the oil temp will climb, but only to the point where the heat can't find easier to take a trip to the cooling jackets. Now once you're elevating the coolant temp, then the oil will be allowed to reach a new state of equilibrium to balance out the distribution of thermal egress.

Quote:
Was the Comment on some days past Thread regarding "Plenty of Engines not running at Normalized Oil Temperature with Oil Way too Thick" made to explain the formation of Sludge? Or, that Oil must be the correct Grade to the Temperature of the Engine?


More than likely the comment was intended to indicate that unless you're driving 20 minutes from a cold start, you haven't reached your visc range. If your driving event is short enough, you may not even be on the SAE scale to fit into a grade. You'll be beyond 70 weight. If that was your common usage, you could probably go down a grade after carefully thinking it out.

It was probably integrated into some debate over heavier oils hurting your engine ..or lighter oils hurting your engine. Everyone transitions through heavier states of visc and their engines survive to tell about it. Not that this revelation is the end all in light bulb illumination, but it needs to be kept in mind to temper other schools of thought you may form ..or have already formed and need to reevaluate.

Sludge, in most instances where we see it today, is more a mismatch and mismash of engine design, engine temp, oil volume, sump size, length of service, fuel/emissions management issues ..negligent consumers using the wrong fluids or assuming that they could treat their new car like they did their old one that was more tolerant of neglect. (visions of I Robot where Dr. Calvin closed her eyes as she fired the machine gun at the NX5 that was about to attack Det. Spooner - "Well, it worked didn't it?"

)

Quote:
Or is this a case of the Temperature will be the same, regardless the Grade, so it is selected Otherwise? -30? -40? -50? And im still amazed at the -20 choices (Logic being 30 turns into a 20, 50 turns into a 40, etc at Temp, "Shears") - ? so "20" does not Shear to a "10?"


Lighter base stocks are required to attain the cold spec's. If your hot spec's require higher viscosity, you're going to tweak the blend with viscosity index improvers. They may shear. As they do, the visc of the oil will start heading toward the visc of the base stock. The bigger the spread, the more vii is used.

The reason it's so easy to have a shear stable 20 grade in conventional oil is that you (could) just make up a batch of 5w30 and forget to put any (less, much less, whatever) vii in it .....voila~ shear stable "otherwise would be shear prone 5w30" 5w-20.

 

[XS650]

Oil temperatures I have seen on cars with oil temperature gauges have always warmed up to higher than coolant temperature unless the car had a big air/oil oil cooler.

 

[Gary Allan]

I've never had -

 

[cheetahdriver]

we have a gentleman on miata.net with a MSM (factory turbo) who occasionally tracks the car and lives in AZ. the MSM is pretty well known to be very light on cooling, and with 0w40 he was seeing 280F oil temps. when he switched to 0w30, the temps dropped to 230F. the inference was that the engine would steady state at an ~8.5cSt oil, and was going to heat anything thicker up until it got there, with the heating mechanism being the relief valve or friction in the bearings.

miata are geared to run ~4000Rpm at highway speeds. while i still like the 0w40 for longer term runs, i have gotten away from a blanket recommendation, lighter can be better...

 

[Jim Allen]

Gary explained it well above. I would only add that engines can be very different and you can guess all you want about yours but you won't KNOW until a gauge is installed. Bear in mind that some PCMs monitor oil temp and you can tap into the OBDII port with something like a ScanGaugeII or a programmer to read it (an other useful readouts). Otherwise, you must hook up a sender (usually in the pan) and install a separate gauge. I found an oil temp gauge useful in verifying my oil viscosity choice.

Also, sludge can come from oil that runs too cool over long periods and it can come from oil that runs overly hot and oxidizes. I think oil does best when it can rapidly reach a minimum 160+ operating temp but seldom exceed the 212F viscosity rating temp. That protects it from both circumstances that can help form sludge.

 

[Gene K]

Question - In heavy diesels Ive seen oxidation is higher than nitration in summer and in winter nitration is higher than oxidation. Can this be used as an indicator? IE excessive spread between oxidation and nitration meaning the oil is being run to hot and a reverse spread the oil is being run to cool?

 

[HangerHarley]

Im starting to think i should ditch Valvoline and just start using Castrol Syntec in my application. Will this be a good idea?

Seems the Normalization thing, i got it. If the oil never warms up, Grade selection may need to be adjusted. Very well explained, Gary!

As for Brand/Type, people have mentioned HDEO. I Think Syntec may be great to suit the task.

Where can i find info on the Castrol Syntec grades?