"Cold Cranking" Viscosity Question 0W30 vs 5W30

[BritGerCarLuvr]

HI there.
Before I ask the question, there are a few things I want to mention, so there is no confusion & we don't turn this into a fiasco.
I know and WANT to use oils that meet Ford WSS-M2C929-A and/or the "new" WSS-M2C946-A which superceedes the previous. I WANT an SN rating and at least a API CF rating. I also want to use an ACEA A1/B1, A5/B5 spec. Therefore, we just knocked out the "High VIS" A3/B3/B4 oils and are dealing strictly with "low viscosity oils". These are what my Jaguar manual requires for both Jags, and that is what I wish to stick to.
My goal is to find the "thinnest" oil possible that meets those specs COLD and that is in the 30 weight category HOT.
My manual "prefers" 5W30, but it also states 0W30, 0W40 & 5W50 as alternatives. I have been running Castrol Edge religiously in both Jags, and changing oil and filter every 5000 miles.
This is mainly about going from 5W30 to 0W30 on the assumption that a "0" W*** will be "thinner" at "cold" startup.
Unrtil this.....Okay lets look at the following:

Mobil 1 5W30 Viscosity @ 40*C, cSt 61.7
Mobil 1 AFE 0W30 Viscosity @ 40*C, cSt 62.9
Castrol EDGE 5W30 Viscosity @ 40*C, cSt 62.6

They all run at or around 10.* HOT, so that's not a big deal. I understand they ALL protect the engine pretty much the same at running temperature. It's the symphony of valvetrain noise at startup I am trying to address, or at least reduce.

Now I ask, How the heck is a 5W30 actually "thinner" than a "0W30" at 40*C?

The whole idea in moving to a "0W" weight is to get a more "liquid" or faster flow at COLD (or starup) over a 5W, at least I thought...

If I read the specs correctly, I basically didn't change anything as far as my fluidity at cold startup if I go from a 5W30 to a 0W30 (according to the specs above) - which is what a "0" weight is all about anyways???

How did they get the "0" weight on Mobil 1 AFE 0W30, when the 40*C viscosity is actually a bit "thicker" or flows a bit "slower" than the 5W30??

That is my main question. Comments & suggestions are welcome.
One "off the wall" question.... even though 0W20, 5W20 DO NOT meet the WSS specs I mentioned earlier, would there be any harm, or what would happen, if I went to a **W20 grade?

Oh and BTW, this is a SUPERCHARGED Jaguar, driven rather enthusiastically at times. So lets keep that in mind.

Thank youin advance for your thoughts.

 

[Quattro Pete]

Originally Posted By: BritGerCarLuvr

How did they get the "0" weight on Mobil 1 AFE 0W30, when the 40*C viscosity is actually a bit "thicker" or flows a bit "slower" than the 5W30??


Your subject asks about "cold cranking viscosity" but then you cite viscosity figures at +40C. Those are two different things.

http://www.uniteasy.com/en/unitsDict/sae_viscosity_grade.htm


The "0W" or "5W" is tested/measured at something like -35C/-30C. It's not necessarily indicative of viscosity at +40C. +40C = +104F. Do you consider it 'cold'? I don't.

"0w" has its benefits in very cold climates. I don't think it matters all that much in Dallas.

 

[CATERHAM]

Agree, you can largely ignore the extreme cold performance stat's, I do even in my colder climate.

Instead look to the oils viscosity index first and HTHS viscosity second. The oil with the hightest VI and lowest HTHS vis will be the lightest on start-up at temp's at least down to the freezing point.

 

[Knox]

+1 to what, Quattro Pete, said.

It doesn't sound like oil is the issue, maybe the filter? Also a hot running Super Charged V8 in texas, it doesn't sound like a good idea to go thinner in the oil.

 

[mechtech2]

Makes me wonder what they will designate oil when it is thinner than '0' cold.

Be aware there are variances in actual viscosity/thickness of various oils at whatever temps. There is some individuality.

 

[CATERHAM]

Probabily the lightest A1/B1, A5/B5 is M1 0W-30 with it's 166 VI and 3.0cP HTHS vis'. I say probabily because it's VI used to be 180 and a few months before that 169, so Mobil spec's bounce around a fair bit.

The odd thing is there aren't any really high VI light 30wt oils.
That being the case all the light 5W-30 oils are pretty close with VI's about 170 and HTHS vis's around 3.1cP.

If you're interested in blends, you could easily make a very light 0W-30 by blending the lightest 0W-20 (Toyota, 214 VI) and a high VI 40wt or 50wt oil. M1 0W-40 (VI 185) is commonly available so a 50/50 blend with this oil will give you a far lighter 0W-30 than anything commercially available with a resulting VI approaching 200.

 

[pbm]

I know that (the older SL) Mobil 1 5w30 flowed better at start-up in the winter temps that I would see in NY than GC 0w30. I found it a little confusing too but I'm told the GC would flow better at -35*F.
Which would flow faster at winter start-up....5w20 dino or 0w30 Mobil 1?
How about 5w20 syn. or Mobil 1 0w30?

 

[CATERHAM]

All typically light 5W-30's including M1, PP, PU etc flow better than GC down to at least 0C for two reasons; lower HTHS vis and somewhat higher VI's. In fact M1 0W-40 due to it's high VI flows better than GC at temps as high as 25C as does PU Euro 5W-40 below 20C.

A 5W-20 dino and most OTC 5W-20 syn's will be lighter than M1 0W-30 down to below freezing, but at some point as the temp's continue to drop M1 0W-30 with it's very low MRV of 13,260cP will become relatively lighter. But that's academic for most of us.

 

[A_Harman]

Originally Posted By: Knox

Also a hot running Super Charged V8 in texas, it doesn't sound like a good idea to go thinner in the oil.


Agreed.

 

[synthetic_crazy]

There is a video on the Mobil 1 website that addresses their 0W oils. In it they state that the 0W is not a thinner oil, rather it is an oil that flows much more quickly under low temperature conditions. I too was perplexed by the viscosity numbers at 40*C, but after changing my oil this past week to Mobil 1 0W-30 AFE, I have noticed it is very smooth on cold start. The mornings here in TX have been in the low 50s, which I know those of you in the frigid north will laugh, but my beloved Corolla likes to make some noise on cold start at temps below 55*F. However, with the 0W-30 it has been very smooth and quiet!

I think I would try a 0W-40 in your Jaguar. Supercharged+Texas summers=a thicker oil than a 30 weight.