Why switch "operating temp" visc in the winter?

[oggb]

I.E. why do some people recommend switching from 5w-40 (summer) to 5w30 in the winter? It seems to me you would get no better cold weather protection from a 5w30, unless you were somewhere in the arctic circle and your oil never got to operating temp.

I'm just wondering because I go to car meets and several people have mentioned doing this. I don't plan on changing my 15w40 summertime/5w-40 wintertime regimen any time soon.

 

[SrDriver]

We are/have run 5W20 year around here in the southeast without issue. That included a few trips up north to Wisconsin for a family reunion for my aunt's 90th birthday in February where the vehicle saw -14 below zero one morning.

 

[beast3300]

I would guess the thicker oil for summer is a old habit to break maybe? I used to run 1030 in the summer per my owners manual (above 60* F) and 5w30 for colder temps (below 60*).

However, since 10w30 is rarely recommended (in the U.S. at least) I just run 5w30 all year. I have been running 5w30 in my Buick since winter of 08 and I see no reason it shouldn't work. Just taking some gas pickup trucks for example. Let's use GM trucks, they have been recommending 5w30 for several years. If a 6L V8 using 5w30 conventional can tow 7,000 lbs (random number), then why can't a passenger car use 5w30 all year round.

Now obviously some engines are harder on oil than others. However, taking a standard consumer: changes engine oil whenever, at whatever place, with whatever oil. And those consumers reaching 200k miles with this practice shows that maybe we (more educated consumers, i.e. BITOG-ers, or what have you) maybe over think, or think we are doing something better.

I guess it's hard to say exactly what it is to answer your question. I might just be babbling....I know I'm drinking so that of course helps.

 

[HangerHarley]

Ive been asking myself the same, regarding 15W-50 and 5W-50. If 5W-50 encompasses the same range, is there any Real benefit to 15W-50 in the Winter? Castrol Syntec is 5W-50 and Pennzoil Platinum is 15W-50.

I believe either one can be used all year. Both are Synthetic or so they say, and im asking what would a Full Syhthetic 15W do in the Winter? My guess is it would be fine, 0 Degrees sometimes -5 ambient outside temps in cold dark night of January and February.

Perhaps it comes down to if Pennzoil Platinum is better than Castrol Syntec. Maybe it is that simple.

 

[aquariuscsm]

A synthetic 5W50 is definitely thinner than a synthetic 15/20W50.

 

[bluestream]

Originally Posted By: JRed
I.E. why do some people recommend switching from 5w-40 (summer) to 5w30 in the winter? It seems to me you would get no better cold weather protection from a 5w30, unless you were somewhere in the arctic circle and your oil never got to operating temp.

I'm just wondering because I go to car meets and several people have mentioned doing this. I don't plan on changing my 15w40 summertime/5w-40 wintertime regimen any time soon.


If you have an oil temp guage, you will note that oil rarely get to "operating temp" in winter conditions

 

[Gary Allan]

Originally Posted By: Bluestream
Originally Posted By: JRed
I.E. why do some people recommend switching from 5w-40 (summer) to 5w30 in the winter? It seems to me you would get no better cold weather protection from a 5w30, unless you were somewhere in the arctic circle and your oil never got to operating temp.

I'm just wondering because I go to car meets and several people have mentioned doing this. I don't plan on changing my 15w40 summertime/5w-40 wintertime regimen any time soon.


If you have an oil temp guage, you will note that oil rarely get to "operating temp" in winter conditions


It may not reach op temp in the summer either. It depends on the trip length. Ambient may alter where it levels off within a few ticks, but won't prevent it from reaching near the same temp (always: conditions and restrictions apply and exceptions too).

Given the unregulated nature of oil temp (for those who do not have regulated oil temp

), it would tend to reduce the amount of heat that the rad has to reject. Otherwise, it would act as a heat sink. I guess if the heater core managed to keep the thermostat closed it would lower it a bit.

 

[Audi Junkie]

I run 5w30 over 5w-40 in winter because it's thinner at start-up.

 

[Gene K]

You run 40 Grade year round. It runs 180F Winter and 200F Summer Oil Temps. Thats roughly the same viscosity as 50 Grade (Summer) and 70 grade (Winter) at rated 100C.

 

[HangerHarley]

Originally Posted By: Gene K
You run 40 Grade year round. It runs 180F Winter and 200F Summer Oil Temps. Thats roughly the same viscosity as 50 Grade (Summer) and 70 grade (Winter) at rated 100C.


I See. If 100 degrees Celsius/Centigrade (Interchangeable words) is 212 Degrees Fahrenheit and the Normal Temp of the Oil, and it "Only" gets to 200 degrees and 180 degrees, then the Oil remains Thicker, respectively, to its SAE 40 number of Kinematic Viscosity?

I think im picking up on this here. BITOG is all Scientific Data and this is a good thing. Methodology is key.

And as long as it does not reach its Flash Point, it wont burn off.. So if Oil gets to around 240 degrees, its a 35-weight or so?

Would really help to know one's car's Oil Temperature, I see. If Only the Heat Range fo Spark Plugs were a clue.

Specific to my car, I never did change them out on the Probe yet. I dont know what the Heat Range on them is either. Sometimes people use Plugs in the wrong Heat Range, or that are too big. That has to affect Oil Temp as well.

 

[Gene K]

Originally Posted By: HangerHarley
Originally Posted By: Gene K
You run 40 Grade year round. It runs 180F Winter and 200F Summer Oil Temps. Thats roughly the same viscosity as 50 Grade (Summer) and 70 grade (Winter) at rated 100C.


I See. If 100 degrees Celsius/Centigrade (Interchangeable words) is 212 Degrees Fahrenheit and the Normal Temp of the Oil, and it "Only" gets to 200 degrees and 180 degrees, then the Oil remains Thicker, respectively, to its SAE 40 number of Kinematic Viscosity?

I think im picking up on this here. BITOG is all Scientific Data and this is a good thing. Methodology is key.

And as long as it does not reach its Flash Point, it wont burn off.. So if Oil gets to around 240 degrees, its a 35-weight or so?

Would really help to know one's car's Oil Temperature, I see. If Only the Heat Range fo Spark Plugs were a clue.

Specific to my car, I never did change them out on the Probe yet. I dont know what the Heat Range on them is either. Sometimes people use Plugs in the wrong Heat Range, or that are too big. That has to affect Oil Temp as well.


Well grade only technically appliess to viscosity at 100C (212F) where 9.3 - 12.49 cSt is a 30 Grade and a 50 Grade starts at 16.30 cSt. I took poetic license above in trying to explain why people might want to change with temperature.

Depending on base stock a 50 grade oil (16.5 cSt @ 212F) may only be 11.0 cSt at 230F. So if you wanted an 11.0 cSt oil you would pick a 30 Grade if you were running 212F oil temps and a 50 grade is you were running 230F oil temps (I dont have a visc clalcultion program or a chart that goes above 230F). If you were going to be running 250F+ you might want a 10W60.

Thats why my new 5.0 Mustang runs 5W20 on the street or drag strip but I would never consider it if I Open Tracked on a road course. Its also why an air-cooled Harley tends to run 50 weight.

 

[hooligan24]

Originally Posted By: HangerHarley




And as long as it does not reach its Flash Point, it wont burn off.. So if Oil gets to around 240 degrees, its a 35-weight or so?

Would really help to know one's car's Oil Temperature, I see. If Only the Heat Range fo Spark Plugs were a clue.

Specific to my car, I never did change them out on the Probe yet. I dont know what the Heat Range on them is either. Sometimes people use Plugs in the wrong Heat Range, or that are too big. That has to affect Oil Temp as well.


Does your vehicle have an oil/coolant heat exchanger? My car is set up to run coolant thru a block where my oil filter mounts. heat gets exchanged between the coolant and the oil, so during normal day to day driving, my oil temps stay within 10 degrees of what my coolant T-stat is rated for.

 

[Samilcar]

Originally Posted By: HangerHarley
Originally Posted By: Gene K
You run 40 Grade year round. It runs 180F Winter and 200F Summer Oil Temps. Thats roughly the same viscosity as 50 Grade (Summer) and 70 grade (Winter) at rated 100C.


I See. If 100 degrees Celsius/Centigrade (Interchangeable words) is 212 Degrees Fahrenheit and the Normal Temp of the Oil, and it "Only" gets to 200 degrees and 180 degrees, then the Oil remains Thicker, respectively, to its SAE 40 number of Kinematic Viscosity?

I think im picking up on this here. BITOG is all Scientific Data and this is a good thing. Methodology is key.

And as long as it does not reach its Flash Point, it wont burn off.. So if Oil gets to around 240 degrees, its a 35-weight or so?

Would really help to know one's car's Oil Temperature, I see. If Only the Heat Range fo Spark Plugs were a clue.

Specific to my car, I never did change them out on the Probe yet. I dont know what the Heat Range on them is either. Sometimes people use Plugs in the wrong Heat Range, or that are too big. That has to affect Oil Temp as well.



http://widman.biz/English/Calculators/Graph.html

I've found Widman's viscosity calculator very helpful. For high temp viscosity changes, set the minimum viscosity to 100°C. Plugging in spec sheet numbers for a 50 weight oil shows it drops from 19cSt at 212°F to 11.4cSt at 248°F, which would be a 30 weight viscosity. A 40 weight oil drops from 14.4cSt to 8.9cSt at the same temperatures.

 

[Jim Allen]

FWIW, my "normal" oil temp drops about 10 degrees for a Northern Ohio winter. Takes much longer to reach operating temp too but eventually gets there. During the summer it runs around 200-210. In winter, 185-195. I run 5W20 in a 5.4L Ford VCT engine.

 

[addyguy]

A 5w30 is still thinner than a 5W-40, that's why.

They both meet the '5W' cold-crank value; but the 5W-40 oil will be thicker overall. Even thought they both meet the 5W value, the 5w30 oil will more than likely have a higher ccs number on this test, not always, but often!