viscosity difference at 0 centigrade?

[gusgeds]

Hi, just a query re 5/40 and 10/40 oils?
What difference in flow rates actual cst and length of time to extuingsh oil pressure light ( 7-10 lbs pressure) could you expect to see at 0 degrees centigrade all things being equal except the viscosity? Thanks in advance,gus

 

[Shannow]

At zero C, I don't think that you'd see a difference.

Haven't seen much difference in moderately sensible ranges (straight 30 to 20W-50)

-7C, a 25W-70 noticeably slowed cranking, and oil pressure build, as well as losing 3MPG.

 

[Pablo]

Totally depends on the oil, not the spec! Sure the oil needs to conform to the specification, but at 32°F some synthetic 10W-40 oils flow better than conventional 5W-40 oils....if there actually is such a thing

 

[gusgeds]

Ok thanks for the replys shannow and pablo,lets say they are both grp 3 acea A3/B3 MB229.1 ? thanks

 

[Shannow]

Zero C won't really be stressing any reputable oils in start-up protection.

 

[Pablo]

Originally Posted By: gusgeds
Ok thanks for the replys shannow and pablo,lets say they are both grp 3 acea A3/B3 MB229.1 ? thanks


There could be a measurable difference in the lab, but that really isn't that cold. So time for the oil pressure light to go out? Who knows? Won't matter much.

 

[Jim Allen]

There was a significant difference in cranking speed and how quickly the oil pressure light went out between 15W40 and 10W30 (both RT HDEO) in my Ford diesel tractor (Dagenham, England built, gusgeds!) at about -17. At that temp I had trouble getting the engine to start. But at 7C, I definitely wasn't having trouble with the 15W40. The winter viscosity spread in my example is about the same as gusged's but ..... I may be injecting the orange into an apple discussion here, huh?

 

[IndyIan]

I have a oil weight chart for the suzuki vitara that says dino 20W50 is good down to -10C...
I'm sure its not ideal but that's the range they give.
Ian

 

[getbent]

At what temperature does a 5W become noticeably better than a 10W?

 

[FrankN4]

Originally Posted By: Pablo
Totally depends on the oil, not the spec! Sure the oil needs to conform to the specification, but at 32°F some synthetic 10W-40 oils flow better than conventional 5W-40 oils....if there actually is such a thing

That is it. For example, Mobil 1 5W-40 TDT has a 0C cSt of 1009.74 and Amsoil 15W-40 AME has a 0C cSt of 907.29. There are lots of other examples but you get the idea.

 

[SubieHo]

Originally Posted By: getbent
At what temperature does a 5W become noticeably better than a 10W?


Here a the parameters for 5W and 10W grade testing: Cold cranking viscosity of 6200 cP @ -30C and 6600 cP @-25C, respectively; Maximum low temperature pumping viscosity of 60,000 cP @-40C and 60,000 cP @-35C, respectively.

If you compare within the Pennzoil Platinum line, both their 5W30 and 10W30 muli-grades share kinematic a viscosity of 10.2 cSt. @100C. At 0 C, the values are 467.92 cSt. and 557.97, respectively. As already stated, there is little "real world" difference between a 5W30 or 10W30 this temperature.

However, the rate of "thickening" increases at more extreme low temperatures (< -20C), which is where the difference between 5W and 10W grades would become apparent.

 

[mva]

My Canadian opinion on conservative min cold start temp vs grade:

0WXX -40C

5WXX -30C

10Wxx -20C

15W40 -15C

20WXX -10C

Individual brands vary, so if you want to be safe and conservative stay 10C above the pour point. Think of thick liquid honey as you approach the pour point. And molasses or roof tar as you go below the pour point.

Keep in mind that thicker oils will cost you in fuel economy.

 

[gusgeds]

Thankyou for all the replys,re Jim,s ford tractor, still plenty of the old blue fords from the sixties and seventies working away on local farms here although to be fair plenty of megabucks 4X4 huge John Deere,s as well! Best wishes gus.