Why 10w30?

its not that 10w-30 was designed for vehicles but that 10w-30 was a common recommendation back then since most people used an oil that was group 1 and 2 based.

A 10w-30 would provide better overall performance and they also had graphs that would say to use a 5w-30 once it hit like -10f or less but to use a 10w beyond that since oils were bad enough then that a 10w really did give better shear resistance,

Nowadays a 5w-30 gives better shear resistance and protection as it needs better base stocks while a 10w doesn't so x blender cheaps out the base stock but charges the same. i wouldn't mind paying less for a 10w though. if not id rather pay the same money and get a better base stock.

It's only with pennozil platinum that i cant be certain. if both their 5w and 10w oils are 100% gtl then that would mean the 10w is better but all others who mix group 2/3/gtl/ehc leave room for debate.
If someone really wanted a 10w-30 with better performance and shear stability than a 5w-30 it can be had from mixed fleet HDEOs.
 
If someone really wanted a 10w-30 with better performance and shear stability than a 5w-30 it can be had from mixed fleet HDEOs.
That is true multi vehicle 10w-30 hdeo's do provide great performance but most will look for gas rated jugs with that number. i wish 10w-30 diesels were a lot more common. id love to throw supertech diesel 10w-30 in my new escalade, civic, and outlander with its volvo vds and ford wss certifications and supposedly its using that good exxon mobil ehc stuff for 2.50ish a quart.
 
Yep, aligns with my understanding as well. I believe there's also a 2cSt GTL base? Perhaps a 3 as well. These Group II+ bases are, as the tables presented show, an excellent compliment to the thinner bases to blend many of the grades you mentioned that may be difficult or impossible to blend with straight Group III.
Yes I agree, lots of potential to blend great Group II+ and Group III semi-synthetics.

BTW not only 10W30 but also 15W40 semi-synthetics, here is another thread where Joe talked about these oils

 
From the above thread:

Q: SR5 -
Warm climate, family car, do you go a Group III 5W30 synthetic for a bit more coin, or a Group II 15W40 A3/B3 mineral for a bit less coin ?

For the Group III 5W30 synthetic, would you select the A3/B4 or the Dexos1-Gen2 version, given the same price ?

A: Joe -
Group III 5W30 (presumably A3/B4) or Group II 15W40 A3/B3? For me, the 15W40 is the better lubricant. Reasons are lower Noack, less VII, marginally more ZDDP & possibly less ashless dispersant (not that big a deal for gas engines, more significant for diesels). Also Group IIs are 'greener' to produce than Group IIIs. Also I'm notoriously cheap!

Group III 5W30 full synthetic A3/B4 vs dexos1-Gen 2? For me, the A3/B4 oil wins BUT these two are so close, there's not a lot to differentiate them. I'd opt for the A3/B4 oil because it HASN'T been put through the US fuel economy tests. I don't like these tests because as often as not, they 'encourage' formulators to drop the oil's CCS viscosity to silly levels to cheat the test. Lower CCS means more VII & higher Noack. The A3/B4 oil might also have a higher ZDDP content (but not guaranteed) & a higher TBN.
 
up there yeah id definitely use a thicker oil than a 20 or 30 grade but the hths doesnt really get better beyond a 15w-40 like chevron delo which is 4.2 and can actually get worse.

i know that gtx 20w-50 is 3.7-3.8 hths so pretty bad for its viscosity. mobil's 15w-50 is 4.5 so its one of the few good off the shelf oils.

Ande Red Line is 6.1
 
That is true multi vehicle 10w-30 hdeo's do provide great performance but most will look for gas rated jugs with that number. i wish 10w-30 diesels were a lot more common. id love to throw supertech diesel 10w-30 in my new escalade, civic, and outlander with its volvo vds and ford wss certifications and supposedly its using that good exxon mobil ehc stuff for 2.50ish a quart.

OP here and my question was really about oils for gasoline vehicles.... But my current love affair after seeing some stunning VOA's and UOA's is Rotella T5 10w30. It is hard to find, but when Autozone or some similar place pops it on sale... I clear the shelves. Yeah, yeah... I know... it has a ton of ZDDP that might destroy the Cat over time, but I don't care.


........
 
OP here and my question was really about oils for gasoline vehicles.... But my current love affair after seeing some stunning VOA's and UOA's is Rotella T5 10w30. It is hard to find, but when Autozone or some similar place pops it on sale... I clear the shelves. Yeah, yeah... I know... it has a ton of ZDDP that might destroy the Cat over time, but I don't care.


........
It would only destroy it if the engines a burner but for a 4 quart jug of syn blend it's quite overpriced at 18 bucks. I wish supertech diesel came in a 10w-30 for its price.
 
The push towards fuel economy and lower viscosity oils is the only reason 10W-30 has a perception of being for older vehicles. This direction in recommendations has not resulted in a halt of bringing 10W-30 or even 10W-40 up to current, modern specs. The 10W-30 in my stash is all API SP or both, SP and GF-6A - thoroughly modern, ready to use in any vehicle calling for those specs.
 
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The push towards fuel economy and lower viscosity oils is the only reason 10W-30 has a perception of being for older vehicles. This direction in recommendations has not resulted in a halt of bringing 10W-30 or even 10W-40 up to current, modern specs. The 10W-30 in my stash is all API SP or both, SP and GF-6A - thoroughly modern, ready to use in any vehicle calling for those specs.
Just purchased some ST 10w-40 for my OPE and was surprised to see it was API SP. The other thing noted was ST no longer sells "conventional". The ST conventional now is semi-syn.
 
The push towards fuel economy and lower viscosity oils is the only reason 10W-30 has a perception of being for older vehicles. This direction in recommendations has not resulted in a halt of bringing 10W-30 or even 10W-40 up to current, modern specs. The 10W-30 in my stash is all API SP or both, SP and GF-6A - thoroughly modern, ready to use in any vehicle calling for those specs.
Exactly. The hysteria over the winter rating is ridiculous.
 
The push towards fuel economy and lower viscosity oils is the only reason 10W-30 has a perception of being for older vehicles. This direction in recommendations has not resulted in a halt of bringing 10W-30 or even 10W-40 up to current, modern specs. The 10W-30 in my stash is all API SP or both, SP and GF-6A - thoroughly modern, ready to use in any vehicle calling for those specs.
I agree completely on all your points.
I too just purchased some 10W-30 semi-synthetic that’s rated API SP and ILSAC GF-6A, a good modern oil.

Any 10W-xx oil is tested for cold starting down to 0F (-20C) which is more than enough for me year round.
 
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Any 10W-xx oil is tested for cold starting down to 0F (-20C) which is more than enough for me year round.
And I think this is what many fail to realize, not everyone has to deal with really cold temps.
I mentioned before, I rarely see temps below freezing, and even with the most severe cold in the past 50+ years this winter, we did not see temps below 14°F (only stayed below freeing for ~48 hours).
And then we were not out driving, roads frozen and unsafe to get on them.
 
And I think this is what many fail to realize, not everyone has to deal with really cold temps.
I mentioned before, I rarely see temps below freezing, and even with the most severe cold in the past 50+ years this winter, we did not see temps below 14°F (only stayed below freeing for ~48 hours).
And then we were not out driving, roads frozen and unsafe to get on them.
0 and 5w oils are more for cold engine convenience and warm up efficiency. They're not necessary but an engine is gonna have a better time with a 0w at 0f warming up and thinning than a 10w.

But people that think that their engine needs 0w-16 in their 30f ambient texas winter temps or their engine is gonna explode are fools.

The mpg during the warm up is nicer with low w rated oil and I think it's more for that reason. Most only drive for like 20ish minutes or less and most cold engines won't have its oil warm up to 100c in that time. Only turbocharged ones really will. I believe thin oils are more for short trip efficiency.

Once the oil is warmed up in the highway there's virtually no mpg improvement from a 10w-30 to a 0w-16 unless you have a very high mpg car to extrapolate the difference. But in the first 10-15 minutes of city driving yeah much bigger difference in mpg and that's what I think the manufacturers are getting at.
 
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