Why would manufacturers specify a 10w-- oil?

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Ringe

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Sorry, the continual search for knowledge here.

I've observed that some older Buicks with the 3.8L v6 recommended 10w-30 oil on the cap. Now, the same motor recommends 5w30 on the cap.

I read this article here: http://63.240.161.99/motoroil/ The author claims that the lower the number before the W the better, because when oil is cold it is way too thick. That's his premise anyway, I don't know enough about it to say if he's correct.

If that is true, and feel free to correct me if I'm wrong, wouldn't it be ok to use 5w30 or even 0w-30 in a car recommending 10w-30? Or do the auto engineers have something going here, requiring a certain higher viscosity at cold temps to prevent some sort of issue?

Thanks for the input,
Ringe
 
Why? Less actual vis loss at the bearings due to less VI improvers.

JMO.
 
Car makers may have specified 10w30 oil when oil was rated SG or something previous to the current SM oils. The same car makers may now specify 5w30 SM oil for the same engine with little or no changes in design.

5w30 oils in their early inception had problems with shear stability that are no longer as problematic with the current SM rated oils.

While it's usually best to not second guess ones owners manual, in the specific case of the GM 3800 it does appear that 5w30 can now be substituted for 10w30. Having said that, it would be wise to closely monitor oil usage when changing oil viscosities and/or changing from dino to synthetic.

Having said that, it also appears that engine builders, car companies, and other interested parties do not always agree. My Mazda owners manual suggest 10w30. The car maker now suggest 5w30 (but specifically not 5w20), yet local mazda dealers put 5w20 in everything that comes in the door. Who is right? That is a question for which i do not have an answer.

In most cases my personal belief is that the differences between using 5w20, 5w30, 10w30, or 20w50 in most engines would not be "drastic" rather it would be increased or decreased wear seen only after tens of thousands of miles.

The differences between using brand X instead of brand Y would be much less measurable, if measurable at all. Yet i'm as guilty as everyone else in here of trying to find the 'perfect' oil for my car for no other reason than it interest me. Im sure my car would run reasonably well for 200,000 miles on 5w30 walmart oil or 12 dollar a quart imported specialty synthetic oil.
 
Early and mid 90s Chrysler 4 bangers called for 10w30 while the whole fleet of V6s in minivans as well as sedans were doing well on 5w30 as speced. Evidently they didn't like paying for rebuilds with their 7/70 warranty.
 
Originally Posted By: hominid7
Car makers may have specified 10w30 oil when oil was rated SG or something previous to the current SM oils. The same car makers may now specify 5w30 SM oil for the same engine with little or no changes in design.


Wrong. Chrysler's SOHC 3.2/3.5 introduced in 98 was spec'd for 10w30 while the DOHC 2.7 introduced at the same time was spec'd for 5w30. The 3.5 is still (2008 model year) spec'd for 10w30.
 
Honda recommends 10W30 in some of it's engines, yet recommends 5W20 in others. I think it has something to do with how well the particular Honda engine does during initial testing, and then stays with that recommendation until that engine is no longer in the product line. I have no doubt that if Honda recommends 10W30 for that new car you just bought, it's a great choice for you to use!
 
I do have to wonder that now Chysler has a lifetime warranty, 30wt oils came back in the manuals for Hemi engines used for towing, where it was only 5w20, 2005-06 manuals.
 
Originally Posted By: Panzerman
I do have to wonder that now Chysler has a lifetime warranty,


LIFE TIME for what?

they must not plan on being in business in the next couple years.
 
Originally Posted By: Loobed
Originally Posted By: Panzerman
I do have to wonder that now Chysler has a lifetime warranty,


LIFE TIME for what?

they must not plan on being in business in the next couple years.


Don't understand the comment? What do you mean by "LIFE TIME for what".
 
Originally Posted By: Loobed
Originally Posted By: Panzerman
I do have to wonder that now Chysler has a lifetime warranty,


LIFE TIME for what?

they must not plan on being in business in the next couple years.


It's lifetime for the original owner only on certain powertrain components only. Basically the only way to win is to have a vehicle and drive it until it needs a rebuilt transmission or engine and you can prove all maitenence was done to spec, and never sell it.
 
Originally Posted By: G-MAN
Originally Posted By: hominid7
Car makers may have specified 10w30 oil when oil was rated SG or something previous to the current SM oils. The same car makers may now specify 5w30 SM oil for the same engine with little or no changes in design.


Wrong. Chrysler's SOHC 3.2/3.5 introduced in 98 was spec'd for 10w30 while the DOHC 2.7 introduced at the same time was spec'd for 5w30. The 3.5 is still (2008 model year) spec'd for 10w30.


While this may be true, generically speaking, the notion that 10w-30 was more shear resistant in older evolutions (mostly) evaporated with advancing base stock technology. You can now (for a while) make a 5w30 where a 10w-30 was as good as you could manage without using a base stock with a lower visc. It would be a sensible notion that a manufacturer would spec the oil with the thinnest start up appearance as long as it didn't compromise operating visc over the duration of the spec'd OCI.

Now surely one or two engines here or there may have their mileage vary in this trend.
 
Originally Posted By: Ringe
I read this article here: http://63.240.161.99/motoroil/ The author claims that the lower the number before the W the better, because when oil is cold it is way too thick. That's his premise anyway, I don't know enough about it to say if he's correct.


That would be the good doctor, Dr. Haas. He is very knowledgeable. Also, he is a prominent member of this forum.
 
Originally Posted By: G-MAN
Why? Less actual vis loss at the bearings due to less VI improvers.

JMO.


Basically they are afraid then that when the VIIs wear out you end up with an oil that is too thin to protect the bearings?...I think I'm getting it. Barely put a dent in Jag's reading list, but there is a ton of info there. Thanks for dealing gently with the Newb folks.
LOL.gif
 
Originally Posted By: Ringe
Originally Posted By: G-MAN
Why? Less actual vis loss at the bearings due to less VI improvers.

JMO.


Basically they are afraid then that when the VIIs wear out you end up with an oil that is too thin to protect the bearings?...I think I'm getting it. Barely put a dent in Jag's reading list, but there is a ton of info there. Thanks for dealing gently with the Newb folks.
LOL.gif



Modern VI improvers are relatively shear stable, so they don't "wear out" like they used to. The problem is that even when they function perfectly, the nature of how VI imporvers work can lead to a much thinner oil film in the bearings versus an oil that has no VI improvers or less VI improvers.
 
I have been using Mobil 1 10W-30 in my 4.9L 1988 E-150 since had had about 20,000 miles on it (it has 64,000 now). I change the oil once a year since it sees only about 500-1000 miles/year driving lately. The owners man specs 10W-30. At a recent visit to Mobil's website they are listing 5w30 as the recommemded oil.

I just changed the oil and used 10W-30. Should I switch to 5w30 on the next OC? Has the 10W-30 done any damage?

On a positive note I have a pre-luber installed and I throw a toggle switch and pressurize the system before I even trun the key.

Confused!
Frank D
 
Originally Posted By: demarpaint
I have been using Mobil 1 10W-30 in my 4.9L 1988 E-150 since had had about 20,000 miles on it (it has 64,000 now). I change the oil once a year since it sees only about 500-1000 miles/year driving lately. The owners man specs 10W-30. At a recent visit to Mobil's website they are listing 5w30 as the recommemded oil.

I just changed the oil and used 10W-30. Should I switch to 5w30 on the next OC? Has the 10W-30 done any damage?

On a positive note I have a pre-luber installed and I throw a toggle switch and pressurize the system before I even trun the key.

Confused!
Frank D


10w30 will do just fine.
 
Originally Posted By: Loobed
Originally Posted By: Panzerman
I do have to wonder that now Chysler has a lifetime warranty,


LIFE TIME for what?

they must not plan on being in business in the next couple years.


LOL.....or next month!
 
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