Yep, the 5W30 is just fine for the car.

 

Mine gets 10w30

 

In some cases yes, but it depends on the brand. Mobil 1's 0w30 is not quite as shear stable as Amsoil's 0w30 for instance, so if you choose Mobil 1 0w30 you're getting an oil that will thin out a lot quicker compared to their 5w30. But in the case of the Amsoil 0w30, it's very shear stable, so it can do everything their 5w30 can do. But it's also a bit more costly too, so that's the drawback there.

In the case of Castrol Syntec 0w30, it's a completely different oil than their 5w30, as the 0w30 is made in Germany and uses an extremely exotic base oil and has a very high quality additive package. This oil greatly outperforms the American made 5w30. I was using this German made Castrol 0w30 in my Corvette for a few years, and recently switched to Pennzoil Platinum 5w30 (not because I was unsatisfied with GC 0w30, but simply because I was curious about PP 5w30 and wanted to try something different to see how the oil analysis results stacked up)

 

I guess for me it depends.

I had a case of Mobil 1 10W-30 and a case of Mobil 1 5W-30. One day I did oil changes to the truck and the Vette. I can't honestly say which vehicle ended up with which oil. Point is, they are both more than suitable for each vehicle. Do you suppose if I mixed them, I'd get 7W-30?

 

Very true! I spoke to a Mobile Technical specialist a while back and he explained that Mobil 1 10W-30 is essentially obsolete. 5W-30 not only pumps up faster, even at 70 degrees F, but also protects as well at higher temps.

There is absolutely NO reason to use 10W-30 in any climate.

 

Yep, the only reason they still carry it is because they know that old habits die hard and that 10w30 is still a very popular selling viscosity. Up until very recently it was the number one selling viscosity, but 5w30 has now taken that spot. It won't be long before 5w20 becomes a lot more common though. And don't be surprised if some new cars start using a 5w10 or 0w10 oil in the next decade.

 

From what I've heard, some dealerships and repair shops here in San Diego still use non-synthetic 10W-30 (vehicles other than Corvettes), even though this is almost never specified in owner's manuals as the preferred viscosity. As you say, old habits die hard.

 

And it's the cheapest oil the dealer can buy. They usually pump it out of barrels and hard telling what it is or where it came from!!

 

No. You would get 7.5W-30, and probably start a new trend in oil for moderately cold climates.

But will it meet the tough GM4718M standards?

 

The issue is not the 5W30 it is the variant of Mobil 1 your got...
I do not think the extended life version meets the GM4718M spec.

 

I use one fill of the 5W30 M1 oil per year. I put about 4K miles per year on the car with close to half of them being track miles. Oil analysis in August and again in December showed the oil was still good and the engine was running as it should.

Bill

 

Just an added perspective:

http://www.idavette.net/hib/C5diy/c5diy1.htm


What Kind of Oil?

Since 1992, the factory-fill oil in Corvette engines, except '92 LT5s, has been a synthetic, 5W-30. Prior to that, as far back as the late-1970s, GM used a petroleum-based 5W-30 in Corvettes, except '90-'91 ZR-1s.

The reason GM recommends 5W-30 is it's the politically correct choice when fuel mileage is a prime consideration. The U.S. Environmental Protection Agency, which oversees fuel economy standards for cars sold in this country and believes 5W-30 oil is a significant energy conservation measure, pressures car companies into 1) using 5W-30s in new vehicles and 2) marketing them to service customers. In response to this pressure, many years ago a policy was made by GM at the corporate level that, with few exceptions, the recommended oil for all passenger vehicles be 5W-30.

When you read the "Maintenance and Lubrication" section of the 1997 Corvette Service Manual carefully, you soon find there are alternatives. The book states on page 0-47, "The recommended SAE engine oil viscosity is 5W-30, however, if the temperature is above -18°C (O°F) 10W-30 may be used." Not only is this true for C5 but the same or similar language appears in owner's or service manuals going back a decade or more.

While we dispose of used oil and filters responsibly, recycle our cans and plastic and keep our room air conditioners set for 78°, the Technical Staff of Vette Magazine cares little about the fraction of a percent better fuel mileage we supposedly gain with 5W30 oil in our Corvettes. It is our opinion that high-performance engines regularly operated in above 0°F outside temperature and in their intended duty cycles will maintain performance longer if an oil of different viscosity range is used.

Any 5W-30 engine oil, including the synthetic in C5s, uses chemical additives, called "viscosity-index (VI) improvers", to widen its viscosity range enough to make it a 5W-30. VI improvers contribute little to lubrication and can make a "multi-vis" oil less effective at high temperatures than an oil without them. This can become a problem when the oil is under high shear loads at temperatures above 225°F. It becomes a potentially damaging problem when oil temp. approaches 300°F. If your oil temperature in the pan is 250°F or above, bet that oil temp in bearings is approaching 300°. Near the piston ring lands and the upper sections of the cylinder walls, it is that or above.

Another characteristic of a 5W-30 that can be a problem in severe service is a relatively high evaporation rate at high temperatures compared to lubricants of more narrow viscosity range. A higher evaporation rate contributes to increased oil consumption and substandard lubrication in areas of high temperature.

There are no VI improvers in quality, 10W-30, synthetic engine oils and their high-temperature evaporation rate is less. Thus, 10W-30 synthetics are better lubricants in severe duty applications. For that reason, we recommend that any C5 owner, and, for that matter, the owner of any Corvette built since GM began telling us to use 5W-30, put a synthetic, 10W-30 oil in their engine.

A good choice is Mobil 1, 10W-30 synthetic. An even better choice is Red Line Oil's 10W-30. While it is a good product, to keep its cost reasonable, Mobil 1 is made with a synthesized-hydrocarbon, base-stock. Red Line uses a more costly, but higher-performing polyol-ester base stock as used in jet engine lubricants. Because of this, Red Line 10W-30 due has slightly better anti-friction characteristics and is capable of lower oil temperatures at a given ambient temperature and engine load. Additionally, at oil high temperatures during severe duty operation, Red Line offers more scuff protection when lubricating main, rod and cam bearings.

The second oil selection issue to address is the Service Manual statement that LS1s operated in North America use only an oil meeting GM Standard 4718M. The Manual also states that oils meeting 4718M might be hard to find outside North America and that LS1s operated in such places can use any 5W-30, 10W-30 or 10W-40 petroleum or synthetic oil meeting API SJ and Association des Constructuers Europeens de l'Automobile (AECA) Standard 3-96.

In a survey of some mass-marketers selling major brand synthetic oils to the DIY, we found synthetics may or may not be labeled as meeting GM 4718M but all meet the American Petroleum Institute's (API) Service SJ and International Lubricant Standardization and Approval Committee (ILSAC) GF-2.

Using information provided by the the GM Powertrain Division and the Lubrizol Corporation, a chemical manufacturer that sells raw materials to the world-wide oil refining industry, we researched these different oil specs.. GMPT supplied the particulars of 4718M and Lubrizol's web site (www.lubrizol.com) had the test sequence requirements for API SJ, ILSAC GF-2 and AECA 3-96.

SJ and GF-2 have only minor differences, none of which affect the ability of oils meeting those specifications to lubricate. 4718M and 3-96 are similar, however, both differ from API SJ and ILSAC GF-2 in two critical measures: 1) the GM and the AECA standards require better performance in high temperature/high shear environments, two conditions present in any engine generating very high oil temperatures and 2) both 4718M and 3-96 require a lower oxidation rate, also a necessity in an engine generating high oil temperatures. Those differences mandate synthetic oil because petroleum-based oils cannot meet the higher requirements. Better high temperature/high shear numbers and lower oxidation rates are characteristic of all quality synthetic oils.

The Vette Technical Staff suggests C5ers looking to buy oil for their LS1s not worry so much about 4718M and look for a major brand of 10W-30 synthetic oil meeting API SJ or ILSAC GF-2. Examples are Red Line, Mobil 1, Castrol Syntec and Havoline Formula3 Synthetic. Those operating their Corvettes outside North America should use an oil that meets AECA 3-96.


Below is in response to his article quoted above.

Hi C5ers-

Based on new public posts on this thread and some private email I got over the weekend, I need to elaborate more on this extended drain interval issue. Also, I need to post a little about oil grades.

First of all, do not, under any circumstances, use a petroleum-based oil (ie: non synthetic) for extended drain intervals. Obviously, no one is going to use a petro-based oil in a C5 or 92-up C4, but many use a high-quality petro oil in other types of vehicles. If you do, observe the manufacturer's recommended interval, which in most cases for engines seeing normal duty-cycles, will be either 6000 miles or 7500 miles. *Only* synthetics can be run to extended drain intervals.

Secondly, Mobil and perhaps some other oil companies have begun to introduce their latest marketing scam, "0W-30" engine oil. This is a multigrade oil that acts like a 0W grade when it's cold and like a 30 grade when it's hot. Only problem is, the only people who need a 0W grade oil are those that operate their vehicles regularly in temperatures of
-20F or below, like--people who drive Vettes in northern Alaska or in Antarctica.

To make a 0W-30 oil, even a synthesized hydrocarbon based oil, requires addition of chemicals called "viscosity index improvers" or VI improvers. They have no lubrication function at all but must be added to chemically alter the oil's viscosity range so it becomes wider--hence, the 0W-30 rating. So, your 0W-30 oil actually has fractionally less lubrication ability than even the 5W-30 the car came with but---Mobil has gotten you to switch and you might even be paying a premium price for additional sever cold weather protection you don't even need.

Ok. Now, let's examine the 5W-30. It also has some of those dreaded VI improvers, but not as much as 0W-30. Why is 5W-30 recommended for your C5? Well, many years ago, during the dark days of the first energy crises your Federal government really leaned on all the car companies to start using low viscosity oils as a way to "save energy. If you have 20 million cars, each using a teensy-weensy bit less energy because they are oiled with 5W-30 vs. 10W-30, that might add up to a measurable enough savings that politicians can pander to the environmentalists a bit that they've forced the big-bad auto industry to do something to save energy.

Reality is that the *best* oil grade, for performance and long-term durability, for a C5 operated in normal duty cycles in temperatures down to 0 deg. F, is a 10W-30 synthetic. The reason for this is a 10W-30 has less VI Improvers than a 5W-30 and, thus, is a better oil in high-temperature, high-shear situations. Some 10W-30 synthetics that use polyester base-stock, such as Red Line, use no VI Improvers at all.

In the case of a car that's operated regularly in temps of -10F to say 40 deg, and sees chronic low oil temps, say 200 deg F and lower, may be better off during starts and warm-up with a 5W-30.

For people that race, or for whatever other reasons, see oil temps regularly at 250 deg or above, need to consider a 10W-40 synthetic. If you see 275 deg, you need an engine oil cooler, not a higher-yet viscosity grade.

cYa Hib Halverson

 

Great info. Thanks!
Ed

 

I don't know what your "credentials" are or where you get the above "information" from, but the mpg difference between 5w-30 and 10w-30 would be hard to measure-------they're both 30 weight oils at operating temps where most of your driving is done. This, alone, makes your following comments at least a little suspect.

Now if we were talking 5w-20 (as Ford likes to recommend) vs 5w-30, then there might be a very small difference.


What is your "source" of information for this? It's my understanding that little (if any) VI improver is used in any good synthetic oil.

Again, the "source" for this "statement" about evaporation? I agree that that there is little or no VI improver in a quality 10w-30 synthetic oil, but neither is there in a quality 5w-30 oil.

If a synthetic molecule can be made to duplicate the viscosity of a 10w-30 petroleum oil, why can't a synthetic molecule also be made to duplicate the viscosity of a 5w-30 oil??

Any car operating at any start-up temperature benefits from a lower first number in a multi-viscosity oil. Oil flows through the engine quicker and provides the proper viscosity for good lubrication quicker with a lower first number.

A table of viscosity vs temperature of a couple of Mobil 1 oils follow:

Temp------5w-30------15w-50

-20----------6284--------21,852
0------------2129---------6462
25------------697---------1836
32------------531---------1348
50------------281----------657
100------------71----------138
150------------27-----------46
175------------18-----------30
200------------13-----------20
225------------10-----------15
250-------------7.6---------11.1

While I didn't get the viscosities for a 10w-30 oil when I requested these from Mobil, the 10w-30 viscosities will be about half way in between the numbers above at the colder temps merging into the same viscosities at the warmer temps. While a 5w-30 is mandatory for reliable starting at really cold temps, it sure doesn't hurt anything at warmer temps.

If an engine has been designed for oil to be at a viscosity of 10-13 cSt at operating temp, then I would prefer the 50 degree start-up viscosity of 281 cSt for a 5w-30 over the likely viscosity of 420-470 cSt for a 10w-30 oil.



While people at warmer ambient temps may not "need" a 0w-XX oil to get their cars started, it will, never the less, improve start-up lube and reduce start-up wear. The prof I had for my internal combustion engine engineering courses would always point out to his classes that more engine wear occurs in the first 30 seconds of running then in the next 30 hours if it isn't shut off (racing engines excluded, of course).



This I agree with. In fact, I'm thinking of switching to Mobil 1 0w-40, but it's not GM4718 approved.



Bottom line, GM says that a 5w-30 oil that meets their GM4718 spec is their preferred oil. The oil life monitor is obviously programmed with this in mind. If a Vette is driven somewhat normally, it will still register 50% life remaining after 5000-6000 miles. That would seem to me that "shear down" and the other theoretical detriments of a 5w oil (compared too a 10w oil) was not of concern to the Corvette engineers. Let's face it, most Vette owners would be more than happy to change at a MAXIMUM of 5000-6000 miles if there were issues with the 5w-30 oil. And tracked cars get changed a lot more often!!!

As a result, the factory recommendation is good enough for me.

It also seems that many Vette owners want to "personalize" their cars with mods and changes------including the oil they use. Most mods, I understand. Sorry, but using an oil in a "street" car that is not the "preferred" oil, I don't understand.

 

I don't believe any of the info posted by El Zappo is personally his as he references sources of both halves of his response. The initial piece is off the Idavette website and the second half is an article by Hib Halverson, a well-known and respected Corvette guru. I was glad to see the Mobil 1 10W-30 info discussed as that is what I had to put in mine prior to bedding it down for the winter and will be running come spring. 5W-30 Mobil 1 was not to be found up here due to a refinery shutdown last fall.
Ed

 

That's great.

As I stated, at the top of my post, this is another perspective.

Also, as C5XTASY, pointed out, my source for this info is included in my post.

If you wish to question my Source's sources, Google: Hib Halverson, you may find a way to contact him.

 

I'm not sure if you're kidding or serious, but I just wanted to point out that when you mix two viscosities of oils you don't necessarily get an oil that's the middle of the two. If you mix 5w30 and 10w30 you'll most likely end up with an oil that would still technically be a 10w30, as it's cold cranking specs would probably not allow it to pass the more stringent tests to qualify as a 5w oil.

 

Well, I did google "Hib Halverson". It appears that he is a very prolific writer about cars and particularly about GM products. I also "googled" Engineer Hib Halverson" and "education Hib Halverson" without learning anything about his background. His writing style would indicate his education was in writing or literature-----and there's nothing necessarily wrong with that.

However, as I said before, there is no mpg advantage to using a 5w-30 compared to a 10w-30 oil as Hib Halverson claims in one of his statements. While a 5w-20 oil may provide slightly better mpg, not so with 5w-30. And (as I said above), with that incorrect statement, all other statements have to be considered accordingly.

I'm confident that the reason for GM and most other manufacturers having gone to a 5w-something oil, is to provide improved start-up lubrication----which is also important in street driven Corvettes.

 

Here, I'll help you. You can PM him.
http://forums.corvetteforum.com/memb...halverson.html

 

This ia very deceptive because although there are more viscosity index improvers in conventional (non-synthetic) 5W-30 oils compared to non-synthetic 10W-30 oils, this is a much different scenario when it comes to the synthetic versions of these oils.

A synthetic requires considerably less VI improver to have the same viscosity index as that of a non-synthetic oil of the same viscosity. Even though the non-synthetic oil VI improvers wears out, synthetic oil is far more stable, thermally.

As I mentioned previously, a Mobil 1 technical applications engineer told me that when it comes to synthetic oil, there is no reason for anyone to have to use 10W-30. This same guy was using 0W-40 Mobil 1 in a very hot Texas climate.

10W-30 is obsolete. Let's move on to the next topic.....