Why use a different weight than manual says?

[ZZman]

I would say for the most part you should run what the manual says.

However oils change over time. We use to not have 5w or 0w oils. Manuals and testing at the time the car was made would not have included these newer oils. So if the manual called for a 10w30 because that was the best that was available at the time should you not run a 5w30?....No.

You might also use a heavier oil when your car gets alot of miles and tolerances increase to help with oil consumption or oil pressure.

 

[Garak]

Originally Posted By: ZZman
However oils change over time. We use to not have 5w or 0w oils. Manuals and testing at the time the car was made would not have included these newer oils. So if the manual called for a 10w30 because that was the best that was available at the time should you not run a 5w30?....No.


Quite right. While oil chemistries and standards have certainly improved, that doesn't mean that 5w30 is "better" than 10w30, since no one will really agree upon what "better" actually means. Chevrolet made the 305 for many years, with several different oil recommendations. I doubt there were huge differences between those that called for SE and those that called for SF, and those calling for 10w30 and those calling for 5w30, for example. While 5w30 certainly was recommended for the newer small blocks, I doubt that every person running, say, a 1955 vintage 265 would have, or should have, run out and switched over to 5w30 for all conditions.

I have no hesitation in using 5w30 in my Ford 300 over the winter. I doubt the manual recommended it (which I don't have in any case). It works for the conditions; in the summer, I also have no hesitation running 15w30 HDEO.

Unless 5w-20 or some other specified grade is a must-have because of a certain valvetrain design, I think people panic too much over viscosity. On the other hand, up here, weather is the overriding factor. That first number is rather important when we get down to -40.

 

[Jim Allen]

A discussion of the highest caliber and best BITOG tradition!

Lots of enlightenment (from my perspective anyway) here too.

I have oil temp gauges on several of my engines and, thus far, the oil charts for those engines have proven to be accurate as far as I can tell. I give them more credence than I once did and believe the base viscosity can be counted upon. From there you adjust according to ambient temp ranges. I cannot account for the accuracy of every chart on every other vehicle, but it seems that there is a lot of fudge-factor built into those recommendations under "normal" circumstances. That's likely why people like us get away with experimentation and why the "great unwashed" gets away with neglect, abject ignorance or outright stupidity. The extremes of heat and cold require special consideration but for people who live in temperate areas, it's a "macht nichts" situation. Only in the temp extremes do you see failures due to incorrect viscosity.

When I made viscosity changes (namely going from 15W40 to 10W30) in a diesel, I looked at oil temp (a product of load and ambient) and oil pressure at as close to 212 as I could get with both 15W40 and 10W30. It took about 18 months because I didn't want to waste the oil, but there was only about a 4psi average difference between the two oils at the highest temps at a specific rpm. I looked at a temp/viscosity chart to plot the actual viscosity at the temps I used and compared it too the drop of oil pressure and try to understand how that relationship works, but I was busy with other things then and decided the difference was too small to matter. Four psi is likely within a margin for error anyway.

One of the best point made is that, with regards to older engines anyway, the general improvement in lube technology can lead to a fair bit of educated alterations that can be made to the oil... especially in the cold temps area. For the most part, going from a 10W grade to a 5W grade would be no problem, if not a welcome improvement for many older engines. There are other factor to consider beyond viscosity, of course

 

[Y_K]

Originally Posted By: Jim Allen
... it seems that there is a lot of fudge-factor built into those recommendations under "normal" circumstances. That's likely why people like us get away with experimentation and why the "great unwashed" gets away with neglect, abject ignorance or outright stupidity..

The best testament to this is the successful experiment that most venerable Mr Gilbert ran with his old Saab for over a million miles in Wisconsin. He did not use the manual recommended oil weight. Neither he does for his new Viggen 9-3 that he got for free from Saab.

I am more concerned with the vodka they dilute our fuel with.
It is hydrophilic to start with. Next thing we know they will add an amphipathic molecule in the mix. Watch for the government run ads "Soap is good for your hands, engine and environment".

 

[1 FMF]

and another thing,

does your owner's manual say you are "required" to use X viscosity oil? Or does it state, the "recommended" oil viscosity is such and such?

The plain & simple fact, which no one here seems to understand and it makes you all look really silly, is that oil viscosity selection is influenced by environmental and operating temperature.
While the owner's manual is dumbed down, the service manual often states proper oil viscosity selection (or recommend viscosity) based on environmental temperature; my GM service manual states this and my nissan owner's (not service) manual even states this. My nissan book calls out 10w-40 for temp's over 32F and for hot weather, 5w30 for below 32F and not as hot- forget what hot temp range but the 10w-40 bar graph exceeds 120F or whatever the chart goes to. And my GM service manual is a testament to gov't influence in CAFE, it has one chart for oil selection based on USA or North America then another for exports, even though there is no change to the engine.

 

[sbergman27]

Originally Posted By: 1 FMF
now think about what's been said for the last 10 years: "you can't use heavier weight oils because newer engines are designed with tighter tolerances requiring thinner oils."

Who has said that? Please be specific.

Quote:
you all have been duped into using lighter weight oils because of gov't enforcement over fuel economy (CAFE).

Oil technologies have changed and improved, in part because of CAFE requirements. (Despite the fact that CAFE requirements have been quite lax over the last 20 years or so.) In the early to mid 20th century, you might have been able to stick your fingers in the oil, rub them together, and tell something useful. Today, it's all about the additive packages. When pressures increase to the point that hydrodynamic lubrication is no longer in effect, the organic moly or other EP additives step in to do the job better than any oil film ever could. Does it even make sense to handle EP conditions with the oil film? Or does it make more sense to design the base fluid not to create excessive drag and let the specialized additives "just handle it" where non-hydrodynamic conditions exist. More and more, it seems to me that the latter makes a lot more sense.

 

[sbergman27]

Originally Posted By: 1 FMF
did you spec a coolant (dexcool) to be run in a whole fleet of engines and screw up on certain models which had incompatible gasket materials?

It was determined that the problems were not caused by DexCool. Certain pressure caps which were being used at about the same time would sometimes pull air in along with coolant from the return tank. Constant exposure of the coolant to oxygen caused the coolant to acidify, as would any coolant under those circumstances. The acid damaged the head gaskets.

 

[1 FMF]

Originally Posted By: sbergman27

Who has said that? Please be specific.


wow, i didn't think i would have to back up this far.
google for starters, it's all preserved on the internet, just search on the word tolerance for incorrect uses of the word

the general perception is this, and it is wrong!

http://classictruckworld.tenmagazines.com/articles.asp?page=tenarticle&aid=2451
Quote:

High viscosity oil in tight tolerance applications can lead to fluid friction increasing oil operating temperature and the oil’s susceptibility to shear


my favorite:
https://bobistheoilguy.com/forums/posts/40719/

posted by Yuk on 8/23/2003, 3:07AM bitog time
Quote:

It is often said on the site that loose tolerance engines may benefit from a W50 oil and tight tolerance engines will do better with a W30


another great WRONG statement, made in 2008
http://www.subaruforester.org/vbulletin/f113/oil-consumption-30012/index2.html
Quote:
Also, it wasn't until recently that engine tolerances were even made tight enough for 5w30 oil... 5w30 really needs tight tolerance between parts otherwise it will burn more quickly.



http://www.royalmgi.com/product_racing-oils.shtml
http://www.peterverdonedesigns.com/motoroil.htm
http://action.publicbroadcasting.net/cartalk/posts/list/2140777.page

here is a good read:

http://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=226497
Quote:

That article gives absurd info - like the "tight tolerance higher horsepower" engine found in the 2001 CVPI.
Are they referring to the same engine used in the 99-00 GT that used 5w30? I think so. The 2001-up Crown Vic motor is nothing more than the Romeo version of the 99-00 GT motor - complete with PI heads and cams. Why use 5W-20 when the same engine used to use 5w30? The internals certainly didn't change to warrant the need for 5W-20.

 

[1 FMF]

Originally Posted By: sbergman27
It was determined that the problems were not caused by DexCool. Certain pressure caps which were being used at about the same time would sometimes pull air in along with coolant from the return tank. Constant exposure of the coolant to oxygen caused the coolant to acidify, as would any coolant under those circumstances. The acid damaged the head gaskets.


ummm, no, that is not the entire truth.
What I was referring to was the 2-eha component of dexcool being a plasticizer and attacking nylon based gaskets, specifically the intake manifold gasket that was initially used in the 3.1L and 3.6L v-6 engines. Once it became a significant problem GM issued a TSB regarding the issue. Ford had realized early on that dexcool had it's issues and decided not to use it, not that I'm in any way saying ford engineers are better than GM engineers. And if you believe the article, it's said there were memos but I'm sure those will never see the light of day that honda issued objections when it's engine went into the saturn vue about the problem with using dexcool but GM used dexcool "because that’s what’s in the plant for everything else."........ which backs up my previous statement that was injustly censored about the reality of engineering and management.

please read motor magazine - coolant confusion
http://www.imcool.com/

 

[1 FMF]

and why was my other 2 posts removed?
the clearance this website allows on posts is starting to reach my tolerance level,

do you know what i am saying?

 

[1 FMF]

( CAFE !!! )

replace "Timmy" with "CAFE"

 

[d00df00d]

Originally Posted By: 1 FMF
and why was my other 2 posts removed?
the clearance this website allows on posts is starting to reach my tolerance level,

do you know what i am saying?

Your posts in this thread have had a fairly high flaming-to-info ratio. Try toning it down a little and see what happens.

You also might want to consider that a few mistakes aren't enough to condemn an entire profession or industry, and that maybe insinuating as such will not go over well on a forum like this.

 

[sbergman27]

Originally Posted By: 1 FMF
wow, i didn't think i would have to back up this far.
google for starters, it's all preserved on the internet,

That's pretty much my point. You implied that manufacturers were using that line. When in fact that assertion has simply been a part of the ever-increasing degree of loose talk flying around on the Internet.

Of course, that doesn't mean that low viscosity oils are bad. Just that that particular reason for using them is not entirely valid. The fact is that oils have become steadily less reliant upon the fluid film itself, and more reliant upon the excellent additive packages.

Less viscous oils have not been foist upon us. They have evolved to meet the necessary requirements to the point that they are desirable. Also note that as river rat pointed out, most Xw20 oils aren't all *that* much lower viscosity than a typical Xw30. I think Mobil's 0w20 is about 20%-25% less viscous than their 0w30.

 

[Bill in Utah]

Originally Posted By: 1 FMF
and why was my other 2 posts removed?
the clearance this website allows on posts is starting to reach my tolerance level,

do you know what i am saying?

I'll PM you if you can not figure out why they were removed. When we get notified we will take action if needed.

Bill

 

[Bill in Utah]

Originally Posted By: d00df00d
Originally Posted By: 1 FMF
and why was my other 2 posts removed?
the clearance this website allows on posts is starting to reach my tolerance level,

do you know what i am saying?

Your posts in this thread have had a fairly high flaming-to-info ratio. Try toning it down a little and see what happens.

You also might want to consider that a few mistakes aren't enough to condemn an entire profession or industry, and that maybe insinuating as such will not go over well on a forum like this.


Excellent answer!