and then Multi Viscosity Base Oil questions

[VaderSS]

I often hear that a 10W30 starts life as a 10 grade oil and then VI improvers are added to make it behave like a 30 grade at operating temperature. I'm guessing this was true with Group I oils, but it seems like the current Group II oils, would start out as a higher grade oil and use less of those improvers.

Is this the case? If so, what grade would a 20W50 or 10W30 start as?

 

[mechtech2]

Dead dinosaurs.

 

[VaderSS]

?

 

[Bryanccfshr]

It Depends. They are bought according to viscositie and quality. THis is a commodity market and base oil is a batch product. Although quality controls can be tight each batch is going to be a little different in viscosity, aromatic content and total saturates and often that batches will be from different plants. The blaneder makes adjustments and may have to blend base oils of differnt viscosities at differnt proportions to get within there blending window to produce the target product.

To answer the OP
THey strart with whatever results in the target quality.

 

[Max_Wander]

Generally speaking though, is Vader right?

 

[Bryanccfshr]

My understanding is that the higher grade the base oil(higher viscosity index) the less VII's needed to make a multigrade. Also some base stocks such as grp II and III react very well with PPD's while most additives increase the Pour point of PAO's.
So yes but it is a simplified description on how they arrive at a product.

 

[Drivebelt]

A 10W-30 doesn't necessarily start out as a 10 grade, in fact, there isn't really a formal 10 grade specification in the SAE J300 standards (the lowest is 20 grade which is 5.6 - 9.3 cSt). There is only a 10W specification.

One can make a 10W-30 synthetic with no VII's like Amsoil 10W-30 ACD. In this case, 30 weight (grade) base oils are used to make a 10W-30. The base oils have a naturally high VI and flow so well in the cold they can meet multigrade specifications by themselves. Synthetics flow better in the cold, so one can use higher viscosity base oils to formulate a synthetic 10W-30 compared to conventional oils. The same is true with Group II base oils vs G1. GII have better cold flow properties, so one can use a little higher viscosity GII's to formulate a 10W-30 versus using G1 base oils to formulate the same 10W-30.

I believe the GII base oils used for a 10W-30 are ~ 5.6 - 5.8 cSt, which would put them near the bottom end of the 20 weight range (5.6 - 9.3). With GI, one would have to go lower and you would likely be ~ 5.0 - 5.1 cSt. So, loosely speaking, the base oils used in a 10W-30 G1 would be a "10" grade (if we made some range for a 10 grade) since they would be just below the 20 grade specification.

The oils used to formulate a 20W-50 -- again it depends on the base oils used. One can formulate a synthetic 20W-50 with no VII's (so the starting base oils would be 50 grade range). My guess is a conventional GII based 20W-50 would probably use base oils ~ 10.0 cSt. (30 weight range) and then use VII's to get to the 50 range.

 

[MolaKule]

A blender or formulator uses the Groff chart to mix various viscosities of oils and additives.


https://bobistheoilguy.com/forums/threads/oil-rheology-ii-groff-charts.41181/

For an idea of viscosites required for gear lubes (a similar process) SEE THIS THREAD:

https://bobistheoilguy.com/forums/threads/gear-tribology-and-lubrication-part-ii.57858/

 

[VaderSS]

Thanks guys. I knew I'd get some good answers.

 

[TallPaul]

Somewhere a general list was supplied (Lubes & Greases, or was it Bruce). I don't have it at my fingertips, but recall that 5w30 started with about a 4.1 cSt (100C) base oil, whereas 10w30 started with a 6 cSt (100C) base oil. This is one reason I prefer 10w30, it has a thicker base oil, so all else equal, will have a higher HTHS.

Straight 30 I think was around 9 cSt base oil (add package apparently brings it the rest of way to a 30 wt). 20w50 probably closer to the 9. If I have time later, I'll post the whole list.

 

[VaderSS]

Thanks!

 

[TallPaul]

Here it is from Lubes 'N' Grease Oct 07:

Grade: 100C cSt base oil viscosity

SAE 30: 9.3
5w20: 3.9
5w30: 4.1
10w30 6.0
10w40: 5.5
15w40: 7.0
20w50 10.2

From my notes it said (not sure if exact quotes):

Chart is 'main base oil viscosity to make each grade. Values are of older formulations data, bu tfairly representative of actual base oil viscosities currently being sed to formulate engine oils.'

'multiviscosity engine oils tend to revert to base oil viscosity under high sheer rate conditions.'

Anyway, looking at the chart and noting the last quote, I don't ever plan on running any 5w20 or 5w30 in my vehicles, except for 5w30 Maxlife Sythetic which is ACEA A3. Actually some HM 5w30s probably are more robust than the 5w30 represented above.

 

[Gary Allan]

Bruceblend® 0w oils. VII's? ..never had them....never will.


(cue Chevy music)

LIKE A ROCK...

 

[MolaKule]

Quote:
Grade: 100C cSt base oil viscosity

SAE 30: 9.3
5w20: 3.9
5w30: 4.1
10w30 6.0
10w40: 5.5
15w40: 7.0
20w50 10.2

From my notes it said (not sure if exact quotes):

Chart is 'main base oil viscosity to make each grade. Values are of older formulations data, bu fairly representative of actual base oil viscosities currently being sed to formulate engine oils.'


Are you sure about the 10W30 and 10W40 starting viscosities?

As was stated earlier, these may be the starting viscosites or the viscosites of highest percentage, but they are NOT the only viscosity USED IN THE FORMULATION or blend.

So don't get the idea you can make an oil with only one viscosity of base oil, except for possibly a monograde synthetic.

 

[TallPaul]

MolaKule, That suprised me also. I figured that the higher amount of VII in the 10w40 thickens too much to maintain the 10w rating unless the base oil is slightly thinner to compensate.

I would assume the base oil viscosities include the interaction of the different weight base oils used, like maybe for a speculative example, the 6.0 for 10w30 represents some 5.5 cSt Group II mixed with a small quantity of 8.0 cSt PAO.

But then all these numbers become meaningless when we look at diffences beween coventiona and synthetic, especially high end synthetic, where the base oils could be considerably thicker and still maintain the "W" rating.

 

[Drivebelt]

Quote:
Here it is from Lubes 'N' Grease Oct 07:

Grade: 100C cSt base oil viscosity

SAE 30: 9.3
5w20: 3.9
5w30: 4.1
10w30 6.0
10w40: 5.5
15w40: 7.0
20w50 10.2

Chart is 'main base oil viscosity to make each grade. Values are of older formulations data, bu tfairly representative of actual base oil viscosities currently being sed to formulate engine oils.


Those 5W numbers are incorrect -- they're either a typo or a misprint. Either that or they are so old they're not relevant any more. YUBASE 4, listed as a 4.24 cSt Group III on their site has a NOACK of 14.9%. A 3.9 cSt Group III would be higher -- over 15% NOACK, so it couldn't even meet the 15% volatility requirement for SM/SL motor oils. So if a 5w-20 was to be blended at 3.9 cSt, you wouldn't even be able to do it with all GIII base oils.

If the numbers were 4.9/5.1 (5W-20/5W-30), then I'd say they're right on. The 10W numbers don't seem quite right either.

 

[TallPaul]

Well, I am sure there is a lot of variance. It would be great to see actual numbers for several oil brands, including conventional and synthetic.