Ultimate Motor Oil Thread or Why we hate CJ4/SM oils

[cnavarro]

Originally Posted by Navaros911

FWIW: The same observations I can make on the Brad Penn oil... my car runs quieter with it. And you know what: I like the sound better that way.

I can help clarify this perception. It is indeed the truth. For every stated viscosity, say 20w50, there is a range of viscosities that can be characterized as being a 20w50, some being closer to a 40 wt and some being closer to a 60wt, at different temperatures, depending on the base stock's Kaufman curve. The higher the ISO viscosity of the base stock, the less viscosity improvers are needed.

A good example of this phenomenon is Mobil 1 0w40. It's barely a 40wt. After very little use, it sheers down to a 30wt.

Castrol GTX 20w50 in our testing sheered down to a 30wt in just 800 miles. That would suggest the base stock has a low ISO viscosity with LOTS of viscosity improvers (which sheer down).

Hope that helps clarify things a little.

[cnavarro]

Originally Posted by BytorJr

Ok, back to reality guys...if one is in Iowa they will have plenty of time for creative writing . I know...why do you think I'm bored enough on Turkey day weekend to be looking at oil? Hopefully me sentence to Iowa won't last much longer.

Seriously though. I guess I'm going to add 2 more oils to the question list.
1) MOTUL 300V 20W-60 (yep, the 60 weight)
2) Total 10w-60 (that stuff for the new M3).

Steve W? Charles N? Any other builders?

Thanks.

Both oils are great, for the right application. The Motul will be better in that it will have less viscosity improvers (because of the narrower viscosity spread).

Unless your ambient air temperatures are very high AND you have very high oil temperatures, I wouldn't recommend running viscosities that high because you'll actually cause more problems that solving.

A good example of this is the new LS7 Corvette engines. They call for a 5w30 oil. If you put in a 15w50 (or 20w50), oil temperatures actually jump 20-25F under the same conditions.

Unless your engine is built with clearances designed to use very thick oils (60wt, 70wt etc), you shouldn't.

[RWebb]

Originally Posted by cnavarro

... After very little use, it sheers down to a 30wt.

...

Charles - the VI molecules are broken by shear forces during use??

or is temperature the main factor causing the viscosity change?

800 miles is amazing BTW; yet another reason to hate Castoroil

[Wavey]

Originally Posted by cnavarro

A good example of this is the new LS7 Corvette engines. They call for a 5w30 oil. If you put in a 15w50 (or 20w50), oil temperatures actually jump 20-25F under the same conditions.

Another example is the small Ford V8 that requires 5W-20 semi synthetic - according to my Ford service manager friend, they were experiencing broken rocker arms with the use of heavier oils.

I tried BP 20/50 after years of M1 use. The BP was definitely more viscous in the pour, and the engine cranked slower and took longer to reach temp. I also had a lot more oil smoke which is why I switched back to M1 (50% 15/50, 50% 20/50 Mcycle).

[cnavarro]

Originally Posted by RWebb

Charles - the VI molecules are broken by shear forces during use??

or is temperature the main factor causing the viscosity change?

800 miles is amazing BTW; yet another reason to hate Castoroil

Both temperature and pressure. For lack of a better description, viscosity improvers are little bits of springy plastic that curl up and stretch out, changing the viscosity of the oil. Under sheer or high temperature, they loose their spring. The oil then reverts back to the viscosity of its base stock.

[RWebb]

thx

I always use the Slinky analogy...

[paulgtr]

I just took the royal purple plunge with a napa gold filter. I did the change today. This is my first change since the engine was rebuilt and broken in this spring. I was running mobil 1 20w50 and mahle filter. Since the weather is cooler now I went with 15w40.
The only difference I saw was a slightly higher oil pressure.
The engine runs great before and after the change. An excellent rebuild by an excellent shop. The oil came out dark and there were minimal shavings on the magnetic plug for the crankcase.

[333pg333]

Here's an interesting link. What do you think to this?

http://www.blackstone-labs.com/Newsletters/Gas-Diesel/November-1-2010.php

[dshepp806]

Originally Posted by paulgtr

I just took the royal purple plunge with a napa gold filter. I did the change today. This is my first change since the engine was rebuilt and broken in this spring. I was running mobil 1 20w50 and mahle filter. Since the weather is cooler now I went with 15w40.
The only difference I saw was a slightly higher oil pressure.
The engine runs great before and after the change. An excellent rebuild by an excellent shop. The oil came out dark and there were minimal shavings on the magnetic plug for the crankcase.

Who's 15W40?

Doyle

[cnavarro]

Originally Posted by 333pg333

Here's an interesting link. What do you think to this?

http://www.blackstone-labs.com/Newsletters/Gas-Diesel/November-1-2010.php

For lots of reasons, not an experiment I would recommend repeating. Nor would Shell...

AV oils use a different additive package to provide anti-wear protection (The anti-wear/anti-scuffing additive- Lycoming stock number LW 16702), and is not visible in UOAs. Another such additive is polyisobutene, which greatly reduces lifter wear.

Just because you don't see it, doesn't mean it's not there.

[ratpiper71T]

I just took the royal purple plunge with a napa gold filter. I did the change today. This is my first change since the engine was rebuilt and broken in this spring. I was running mobil 1 20w50 and mahle filter. Since the weather is cooler now I went with 15w40.

The only difference I saw was a slightly higher oil pressure.

The engine runs great before and after the change. An excellent rebuild by an excellent shop. The oil came out dark and there were minimal shavings on the magnetic plug for the crankcase.

FWIW, in my opinion, royal purple is a fantastic motor oil and their products. I've had good experiences with every product of theirs that I've used. Since it supposedly has the sufficient additive package, I will probably use it in my rebuilt flat six, (if they're still making it when I get that done anyway)
I know the sound factor can be subjective, but the difference between this oil and others in every motor I've put it in is- other synthetics, a stressedout POS, RP= a smooth-reving race machine! Lame, I know... But this is what I've heard, others with me have made similar comments.

[paulgtr]

Originally Posted by dshepp806

Who's 15W40?

Doyle

Royal Purple 15w40, sorry for the confusing post. and I am using a napa gold filter.

[BytorJr]

Charles, thank you for your answer.

Looks like I'll be switching from Castrol 20w-50 Syntec to either V-twin 20w-50 or Motul 300v 15w-50 in my '85 911. Funny thing is, Motul isn't that much more than V-twin.

Just not sure how much ZDDP Motul has or even if it's necessary with that formulation. I haven't run into any oil temp issues since putting the big MOCAL up front even after 30 minutes of track session in Florida!!

[Trackrash]

Any comments on Mobil racing? Advertised as twice the zinc.
Mobil 1 Racing Oils

[cnavarro]

Originally Posted by Trackrash

Any comments on Mobil racing? Advertised as twice the zinc.
Mobil 1 Racing Oils

I'm sure they are great. The current motorcycle formulations are what the old racing oils were.

The new racing oils are likely non-detergent or very close to that, with even higher levels of anti-wear additives. Kind of pricy though.

[HarryD]

Originally Posted by 333pg333

Here's an interesting link. What do you think to this?

http://www.blackstone-labs.com/Newsletters/Gas-Diesel/November-1-2010.php

IMHO Lousy science, lousy editorical control by Blackstone.

My (and others) thought can be seen here: Blackstone and ZDDP

[donstevens]

Originally Posted by cnavarro

Both temperature and pressure. For lack of a better description, viscosity improvers are little bits of springy plastic that curl up and stretch out, changing the viscosity of the oil. Under sheer or high temperature, they loose their spring. The oil then reverts back to the viscosity of its base stock.

Charles,

Doesn't the quality of the VI additive add in as a factor?

Don

[cnavarro]

Originally Posted by donstevens

Charles,

Doesn't the quality of the VI additive add in as a factor?

Don

That's a great question and one for the real experts. I would imagine there just might be a difference, but since there are only several manufacturers of base stock as well as additives (4 come to mind), anything is possible.

[68redlines73]

Originally Posted by cnavarro

I can help clarify this perception. It is indeed the truth. For every stated viscosity, say 20w50, there is a range of viscosities that can be characterized as being a 20w50, some being closer to a 40 wt and some being closer to a 60wt, at different temperatures, depending on the base stock's Kaufman curve. The higher the ISO viscosity of the base stock, the less viscosity improvers are needed.

A good example of this phenomenon is Mobil 1 0w40. It's barely a 40wt. After very little use, it sheers down to a 30wt.

Castrol GTX 20w50 in our testing sheered down to a 30wt in just 800 miles. That would suggest the base stock has a low ISO viscosity with LOTS of viscosity improvers (which sheer down).

Hope that helps clarify things a little.

Interesting stuff. Two questions:

1) If you had a product with a base stock combo that was a 60 wt, how could you create a 20W-50?

2) Could you provide additional detail on the 800 mile shear down on the Castrol 20W-50? Test conditions, for instance.

Appreciate your knowledge!

[cnavarro]

Originally Posted by 68redlines73

Interesting stuff. Two questions:

1) If you had a product with a base stock combo that was a 60 wt, how could you create a 20W-50?

2) Could you provide additional detail on the 800 mile shear down on the Castrol 20W-50? Test conditions, for instance.

Appreciate your knowledge!

I have the UOA results on the oil page on our website, somewhere anyways...

I'm not saying that you could start with a 60wt and have a 20w50 (well technically you can), but that the spec for a 50 wt has a range as does 60 wt, and the high end of one can cross over into the low range of the other.