Optimized usage of petroleum oil grades as a function of ambient temps

[TooSlick]

If I were going to use petroleum oils in a new engine, here's what I'd probably due, given the data I've seen:

Expected Ambient Temp During next oil change interval:

< 40F, use 5w-20/5w-30

40F-70F, use 10w-30

> 70F, use a 15w-40 commercial engine oil (CI-4/SL rated)

I believe this will get you the most consistent oil pressure and excellent wear protection throughout the year. I have no issue with running 5w-30 or even 0w-30, PAO/Ester synthetics year round. However, I don't think if you live in a very cold climate you should be running the same petroleum oil you would in Florida or south Texas.

TooSlick

 

[JB]

Just curious, what would be the basis of choosing the oil weights for the temperatures that you listed? Is there an SAE guide or something to say that for a given ambient temperature the right oil must be so-and-so viscosity or HTHS, etc?

This issue is of particular interest to me because where I am the year round ambient temp is 86-90°F. It used to be that the most common oils were xxW-50. Now we're seeing some 5W-30 in the market which many reckon is "too thin". But I've checked with the makers and they all say it is ok.

One said that the temps in an engine are far higher than ambient and the engine's proper operating temp will be about the same regardless in winter or summer. So if an oil can survive the operating temp in an engine in winter (say a 5W-30) no reason the same oil cannot survive the operating temp in summer since the operating temp is nearly the same. Sound logical to me.

Another maker said the 5W-30 oils are approved for all year round use in USA and in summer temps can hit 90-100°F (or more). So if the oil can survive an American summer, no reason it can't work here.

Thoughts are appreciated.

 

[cheeks]

TooSlick, I'd like to use 15W40 in my 1999 5.7L Chevy Suburban, as per your comments, but the Owner's Manual specifically states "Do not use SAE 20w50 or any other grade oil not recommended". The two grades listed are 5w30 and 10w30, with the 5w30 being listed as "preferred".

What's your take on this?

Here's a copy of that page of my manual, but it's hard to read due to size:

http://www.f150online.com/galleries/images/2317-3739-54839.jpg

 

[ondoy]

My 2 cents worth.

Similar to the environmental situation where JB is in, our ambient temperature most often, is in the vicinity of the lower thirties, in degree Celsius. No winter, but all-year round warm climate.

Isuzu, requires either a 5W-30 or a 10W-30 engine oil for my 3.0L, turbo-charged, inter-cooled, common-rail, direct-injection Trooper diesel engine, no matter where in the world this vehicle is being used. It appears that Isuzu sees no reason to specify different oil viscosities for use in different locations in the globe. Currently I am using Rotella T multigrade SAE 10W-30 API CI-4 dino with no problems. Judging from the published specs of Castrol Elixion synthetic SAE 5W-30 API CI-4 oil, it appears that this one is a serious candidate for my Trooper. Once my Rotella is exhausted, the Elixion will surely replace it.

As aptly mentioned by JB, the engine operating temperature (inside the engine) does not vary much whether the engine is operating in winter or summer. So why use oils of different viscosities in response to ambient temperature?

Simply said, it is most prudent to follow the recommendations of the engine manufacturer.

ondoy.

 

[Justin]

quote:

---

Originally posted by cheeks:
TooSlick, I'd like to use 15W40 in my 1999 5.7L Chevy Suburban, as per your comments, but the Owner's Manual specifically states "Do not use SAE 20w50 or any other grade oil not recommended". The two grades listed are 5w30 and 10w30, with the 5w30 being listed as "preferred".

What's your take on this?

Here's a copy of that page of my manual, but it's hard to read due to size:

http://www.f150online.com/galleries/images/2317-3739-54839.jpg

---

TooSlick...you say about 70 degrees to run 15w-40?? Sorry, but what the heck are you talking about?? I run 15w-40 in MUCH, MUCH colder temperatures than that.

And Cheeks, feel free to run "fleet" 15w-40 in your Silverado...the 30 weight ratings are mostly there for maximum cold-startup protection and fuel economy. Chevron Delo 400 is my recommendation. In the winter though, you might want to run a lighter grade for better startup protection in that Chevy.

[ March 25, 2003, 11:34 PM: Message edited by: Justin ]

 

[Quick_lude]

How about the 0w/5w-40 from M1 or Amsoil 10w40 for 40F+ ?

 

[White 03]

I can understand fiddling around with the lower or start up weights; 5w,10w,15w. My question is how much does oil change at high outside temperatures. Put another way, how much, if any, higher is the oil temperature on a 100 degree F day compared to a 50 degree day? Considering that my water temperature is regulated by the thermostat and usally never changes summer or winter wouldn't the oil temperature also stay as consistant. I guess if I had a good oil temperature gauge I could answer my own question.

[ March 26, 2003, 09:21 AM: Message edited by: White 03 ]

 

[Dr. T]

I think the question here has to do with how the ambient temp. has an effect on the higher number eg. 5w-x.

I believe that thinner oils eg. 5-30 may be acceptable at extreme cold whereas the same engine may require a 50 weight in the summer because when the engine is turned off and it's 120F outside, the oil is baking inside the engine as it will take longer to cool (and in fact, the temps. may even go up dramatically) compared to a winter climate/temps as the cooling system is no longer functioning. ie. we've seen this in Turbos and in cars eg. Euro cars that have aux. fans running after shut-down to ensure engine cooling in extreme heat.

 

[buster]

I'm about to run Delvac 1 and temps. will be around the low 30's at night to upper 50's all next week. Should be fine as it's a 5w oil.

 

[sprintman]

Will you get oil analysis on the D1 when finished?

 

[buster]

I'm thinking about it. Does D1 alow extended drains in gas engines as well,with 4qt. sump capacity???
I've narrowed my choices down to D1 in summer for any car/truck I ever own and M1 5w-30 in the winter or Amsoil 5w/10w-30. My only concern is that D1 is too thick for a Toyota engine...oil pump and clearances. It's also hard to get D1 around here. My wife's car runs Amsoil and I will have to place another order soon. S3000 looks nice too but expensive!

[ March 26, 2003, 06:55 PM: Message edited by: buster ]

 

[Toy4x4]

buster,
I believe our friends from "down under" would be able to tell you that their Toyota manuals recommend up to a 50w oil during hot weather so running D1 shouldn't be a problem.

 

[Jimbo]

The US automakers tend to tell you to run 5W-30 or 5W-20 (Ford) in everything no matter what the outside temperature. I fear that this is CAFE driven.

Here is what my 1992 BMW owners manual says.

"The chart indicates the SAE grades to be used depending on the predominant air temperature. The temperature set by the SAE grades may remain under or exceed the limit for a short period."

-40F to +15F 5W-20
-40F to +20F 5W-30
-20F to +40F 10W-30
-20F to +60F 10W-40
-5F to +90F 15W-40
-5F to +105F 15W-50
+15F to +120F 20W-50


15W-40 is the grade of non-synthetic currently sold by BMW in the US. I use 15W-40 Delo all year.

This was before synthetic was factory fill. They do mention "Special low-friction lubricants individually approved by BMW" for the range -20F to +90F.

 

[TooSlick]

I probably made this idea too complicated ....

The point I was trying to make is that if the manufacturer recommends only one viscosity, say 5w-30, regardless of the ambient temps, then it is clearly a compromise viscosity. It is based on achieving acceptable engine life, optimizing fuel efficiency and insuring easy cold weather starting. In the case of 5w-20/5w-30 grades, I'd say the latter two considerations are weighted more heavily than acheiving optimum engine life.

I do think there are some tangible benefits (reduced wear and oil consumption) to going up and down one grade between winter and summer. A simplified version of what I posted above would be to switch back and forth between a 5w-30 and a 10w-40 or 15w-40 at say 50F. There is nothing special about that 50F temp, I could just as easily used 40F or 60F, but you get the idea.

Peak oil temps can vary by 15F-25F, depending on ambients temps. The thermostat does control the lower engine temp to some degree but is does not control the upper engine temps. The difference in viscosity between a 5w-30/10w-30 and a 15w-40 is also about 20F. In other words, a 5w-30 tested @ 190F will have approx the same viscosity as a 15w-40 tested @ 210F.

So going up and down one SAE grade between winter and summer makes perfect sense ....

TooSlick

 

[sprintman]

Buster what is the exact model no of your toyota engine?