Interesting Temperature-Viscosity Chart

[edhackett]

Here's the recommended viscosity grades for given ambient temperatures for my 1991 BMW K100. This is a 1000cc, water cooled, inline four cylinder, with a four quart sump capacity.

Notice the complete lack of trust in multi-viscosity oils. They allow for it to shear back to its base viscosity. This is assuming mineral base and service grades SE, SF, SG.

SAE 20: -10 to 20C
SAE 30: 0 to 30C
SAE 40: 20 to 50C

SAE 10W30: -30 to 0C
SAE 10W40: -30 to 5C
SAE 10W50: -30 to 10C
SAE 15W40: -20 to 20C
SAE 15W50: -20 to 30C
SAE 20W40: -10 to 30C
SAE 20W50: -10 to 40C

Ed

 

[Jeffrey Behr]

quote:

---

Originally posted by edhackett:
Notice the complete lack of trust in multi-viscosity oils. They allow for it to shear back to its base viscosity.
Ed

---

Huh? I see 7 different multiviscosity oils listed. They all apply to a temperature range that's equal to or (usually) greater than that listed for the single-vis oils. I'd say your conclusion is exactly backwards.

I agree somewhat with your "They allow for it to shear back to its base viscosity" statement, but you leap too far in your statement IMO. Certainly the viscosity-index improvers (VIIs) used in most Dead-Dino and some synthetic oils can get shortened ('sheared') and then do not as well at thickening at higher temps, but I simply wouldn't jump to your conclusion. I have seen used DD oils that have lost a degree of hi-temp rating, for instance a 10w30 having a 20-vis hot rating, but they don't just ALL get consumed/'sheared'. I'm not saying VIIs are good, just that they don't behave as badly as you indicate.

 

[edhackett]

Jeffry, look at the maximum temperature listed, not the spread. A straight 40 is listed up to 122F, 10W-40 is only listed for use up to 41F.

SG oil was the current rating at the time, but these listings allow back to a SE rating, which was 1970's technology. Given what we now know about multi grades of that era, maybe those German engineers knew what they were talking about.

I agree that those recommendations are not realistic with the current multi grades.

Ed

 

[cryptokid]

i can understand their lack of trust for the multi vis oils of the time. this tempature chart is probably no longer valid with todays multi vis oils which i assume hold their intended grade far better than yesterdecades oils.

 

[Motorbike]

In the link provided you'll see this Motorcycle engine killed the Delvac 1300S 15w40 in 3k miles shearing it down by 2 cSt's . You will also see that the Delvac uses almost 1k ppm more zinc than the thinner at both 40c and 100c Rotella 5w-40 which faired better in both wear and shear in the same engine , a Honda 750 Nighthawk with hydraulic lifters . These particular engines are pretty easy on oil too compared to some other engines out there .

If the vi improvers are better in the Delvac 1300S than in distant past oils I suppose the old stuff was pure junk

Bike analysis

Bikes are fun but click below for an alternative to your current weekend fix

High Risk out of Oklahoma

[ March 07, 2004, 07:31 AM: Message edited by: Motorbike ]