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Discussion Starter · #1 ·
I know several guys changing out from Mobil 1 to a 15W45 weight oil with better friction additives such as zinc. I was looking for pros/cons to this idea. It sounds good but not enough of a expert in this area to jump the bandwagon....opinions??
 

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Dropped you a PM answering your question there, but providing more data here for all to see.

This is a complicated question with many tradeoffs involved, including owner's manual requirements and warranty coverage, anti-wear additives, CAFE ratings, and hot and cold viscosities.

Your owner's manual requires a 30 grade oil oil meeting GM Standard 4718M. The current API SM/ILSAC GF-4 standards limit an oil's primary anti-wear additive (ZDDP) to 0.08%, or 800 ppm. To use an oil with a higher level of ZDDP will require going against the owner's manual, which most people are uncomfortable with.

Warranty. It is interesting to note that using aftermarket parts does not in itself invalidate your warranty. Not sure of the wording in the C6 Z06 warranty, but here are the applicable words in my 02 Z06 warranty "Damage caused by failure to follow the recommended maintenance schedule intervals and/or failure to use or maintain fluids, fuel, lubricants, or refrigerants recommended in the owner's manual is not covered." Note that it says "Damage caused by... is not covered.". If you have engine failure while failing to follow the requirement for a 5w30 meeting GM Standard 4718M, then GM should not replace the motor if the oil caused the damage. In all other cases, they should replace the motor. Most people won't want to go to bat against GM on this issue, and will thus feel more comfortable sticking with the owner's manual requirements.

CAFE. First, I feel that CAFE ratings are driving auto maker fluid recommendations. Viscosities of oil and tranny fluid are coming down as each drop helps the companies overall CAFE rating. Look how many manufacturers are recommending 5w20 oils now. Dexron VI has a lower viscosity than Dexron III, again, I feel to improve CAFE. While a 40 grade oil might work better in the motor, how much better for a daily driver (which is what GM warranties)? Will a stock motor last 100k miles with a 5w30 when used as a daily driver? If so, then the company can take the 5% or so improvement in fuel mileage a 5w30 brings to the table with little risk (as opposed to a 5w40).

Viscosity. I feel that a stock LSx works well with an oil that has a viscosity of 10-11 cSt, which is what a 30 grade oil's viscosity is at 212F. But how hot does your oil get when you are running your motor hard? Even with an oil cooler, I see oil temps of 250-270F on the track. 300F is common for those guys without oil coolers. At 300F, a 30 grade oil has lost about 70% of the viscosity it had at 212F and has a viscosity of about 3 cSt. That's roughly equivalent to the viscosity a 5 grade oil would have at 212F. How many of you would be comfortable running an SAE 5 oil in your cars? This is one of the primary reasons I run a 40 grade oil in my car on the track. Don't see oil temps over 212F? Then a 30 grade oil might be a better choice for you.

Anti-wear additives. As mentioned above, the EPA mandates that smog equipment function for 100k miles. One of the primary anti-wear additives, Zinc dialkyl dithio phosphate or ZDDP, damages catalytic converters. To ensure their catalytic converters can last 100k miles, the auto industry requested that the API and ILSAC limit the amount of phosphorus in 30 grade oils to 0.08% or 800 ppm (actually they asked for even lower but a compromise was reached at 800 ppm). The new API SM/ISLAC GF-4 oils thus are limited in their primary anti-wear additive to 800 ppm. Most oils used to run 900-1000 ppm and some such as AMSOIL were in the 1000-1200 ppm range. Note that this only impacts 30 grade oils. But, don't assume that 40 grade oils will have higher ZDDP. This is very brand dependent. There are ways around this issue. High Mileage oils usually are not API SM compliant. Diesel CI-4 oils do not have the same limit (but note that newer CJ-4 diesel oils have a similar ZDDP limit - so oils dual labeled as CJ-4/CI-4 are probably not a good choice).

FYI, these AMSOIL products all have high levels of ZDDP (about 1265 ppm phosphorus and 1378 ppm zinc):
AMSOIL Series 2000 20w50
AMSOIL SAE Synthetic High Performance 20w50
AMSOIL SAE Synthetic Premium Protection 10w40 (I ran this oil in my stock LS6 02 Z06 the last few seasons I raced)
AMSOIL Series 3000 Synthetic 5w30 Heavy Duty Diesel Oil

I found this handy table on Mobil 1's website the other day for those who prefer Mobil 1 products (hoping the mods will leave this link since it is to the factory fill oil):
Mobil 1 ZDDP Levels

I personally believe the High Temp High Shear (HTHS) rating of an oil is a good indicator of how the oil will perform in the engine, particularly for those running the car hard. The High Temperature/High Shear Test measures a lubricant’s viscosity under severe high temperature and shear conditions that are similar to severe service applications in an engine.

Putting this all together using some common Mobil 1 products:
Pulled this data off Mobil 1's website:
Oil 100F viscosity 212F viscosity Phosphorus HTHS
Mobil 1 15w50 131.2 18.1 1200 ppm 4.5
Mobil 1 High Mileage 10w40 98.16 14.71 1000 ppm 4.06
Mobil 1 0w40 78.3 14 1000 ppm 3.7
Mobil 1 5w30 64.8 11.3 800 ppm 3.09

So, which one is right for you (assuming you don't care about owner's manual requirements), I'd say the answer is different for everyone depending on their use. I would look at oil temp, thus viscosity, which can be indirectly determined by oil pressure and determine what grade oil to use. On the track in my 02 Z06, I use a 10w40 with high ZDDP as my oil temps are around 250-270F. In my under warranty daily driver 06 CTS-V (LS2) I use a 0w30 which meets GM Standard 4718M. Once out of warranty, I'll consider a 5w40 as a compromise between good flow at cold temps and good protection at high temps.

Not that HTHS ratings are the only factor I considered when making my own oil choices, but I feel that they are telling as to impacts of brand, API rating, application (note that high mileage and CI-4 diesel oils tend to have higher HTHS ratings than their automotive peers), and viscosity grade.

The below HTHS ratings were pulled straight of the corporate websites of the various companies.

Amsoil Series 2000 20w50 (API SM) – 5.8
Amsoil Premium Protection 20w50 (API SL) – 5.0
Amsoil Marine Synthetic 10w40 (API SL) – 4.6
Mobil 1 EP 15w50 (API SM) – 4.6
Pennzoil Marine SAE 40 (API SJ) – 4.5
Mobil 1 15w50 (API SM) – 4.5
Amsoil Heavy Duty Diesel 15w40 (CI-4+) – 4.4
Amsoil Premium Protection 10w40 (API SL) – 4.3
Amsoil XL 10w40 (API SM) – 4.3
Pennzoil Truck/SUV 15w40 (CI-4+) – 4.3
Pennzoil Long Life Heavy Duty 15w40 (API SL) – 4.3
Amsoil Premium Diesel 5w40 (CJ-4) – 4.2
Mobil 1 High Mileage 10w40 (API SL) – 4.06
Pennzoil Marine 15w40 (API SL) – 4.0
Amsoil European 5w40 (API SM) – 3.7
Mobil 1 High Mileage 10w30 (API SL) – 3.66
Amsoil Marine Motor 10w30 (API SL) – 3.64
Mobil 1 0w40 (API SM) – 3.6
Amsoil Heavy Duty Diesel 5w30 (CI-4+) – 3.5
Pennzoil Long Life Heavy Duty (API SL) – 3.5
Pennzoil Marine SAE 30 (API SJ) – 3.5
Amsoil Signature Series 0w30 (API SM) – 3.2 (meets GM Standard 4718M)
Amsoil SAE 10w30 (API SM) – 3.2 (meets GM Standard 4718M)
Amsoil SAE 5w30 (API SM) – 3.2 (meets GM Standard 4718M)
Amsoil XL 5w30 (API SM) – 3.2 (meets GM Standard 4718M)
Amsoil XL 10w30 (API SM) – 3.2 (meets GM Standard 4718M)
Amsoil XL 5w30 (API SM) – 3.2 (meets GM Standard 4718M)
Pennzoil Platinum 10w30 (API SM) – 3.15 (meets GM Standard 4718M)
Mobil 1 10w30 (API SM) – 3.14 (meets GM Standard 4718M)
Mobil 1 EP 10w30 (API SM) – 3.1
Mobil 1 EP 5w30 (API SM) – 3.1
Pennzoil Platinum 5w30 (API SM) – 3.1 (meets GM Standard 4718M)
Pennzoil Truck/SUV 10w30 (API SM) – 3.1
Mobil 1 5w30 (API SM) – 3.09 (meets GM Standard 4718M)
Mobil 1 Truck/SUV 5w30 (API SM) – 3.09
Pennzoil Truck/SUV 5w30 (API SM) – 3.0
Mobil 1 0w30 (API SM) – 2.99 (meets GM Standard 4718M)
Amsoil SAE 0w20 (API SM) – 2.8
Amsoil XL 5w20 (API SM) – 2.7
Mobil 1 EP 5w20 (API SM) – 2.7
Mobil 1 5w20 (API SM) – 2.62
Mobil 1 0w20 (API SM) – 2.61
Pennzoil Platinum 5w20 (API SM) – 2.6
Pennzoil Truck/SUV 5w30 (API SM) – 2.6
Pennzoil Platinum 0w20 (API SM) – 2.6

Note: Many companies such as Castrol, Shell, and Royal Purple do not list HTHS ratings
:cheers:
 

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Discussion Starter · #4 ·
Brad
Thanks for the detailed reply. I will think hard about your opinion and recommendations. Every driver and intended use for these cars can be very different and the oils should reflect this accordingly (over GM specs if necessary). I think alot of guys are afraid of their GM warranty but are not willing to admit it.

Thanks again and I hope this will help other guys that have the same questions.:z:
 

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Brad
Thanks for the detailed reply. I will think hard about your opinion and recommendations.
My pleasure and good luck with your decision. I know it is not easy.

To throw some more confusion out there, here is what GM does when CAFE isn't involved.

This quote is from a guy in Scotland on another Corvette forum (I can give the link via PM):

"For your information, here`s a couple of photos of a sticker on the door pillar of my June 2007 Euro spec C6Z06 - hope this helps"

And here is his photos:




:cheers:
 

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Here's another little tidbit of info from another forum I used to peruse once in a while... although they deal with higher stressed V6 engines in import performance cars, several owners from that forum that used Mobil 1 5w-30 or 10w-30 had VERY high wear metal readings when UOA's (Used Oil Analysis) were done. Those same owners had much better UOA's just by switching to Mobil 1 0w-40 Euro spec (as well as a few other oils such as Amsoil Signature Series 0w-30). The theory there was that Mobil 1 5w-30 was shearing down when pushed &/or just too thin at high temps. Either way results in metal to metal contact at high revs with hot oil.

I agree with those that have said that GM's 5w-30 rec is based on many factors OTHER than just engine reliability. It's a good thin oil that does well for street use & is good for economy.
 

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It sounds like the the best of both worlds is a synthetic with good additives and a higher weight (number on the back end) for high temperature stress viscosity or a 40 weight.
Any other input would be appreciated....
It really depends how you're going to drive the car (street, cruise, or tracked hard) and the external temps. If the oil gets too hot it'll thin down to water & can't provide sufficient film strength for proper protection. The HTHS rating is a good way to compare this aspect.

Personally, I use Amsoil 5w-30 Heavy Duty Diesel oil, which has very similar viscosity numbers to Mobil 1 5w-30, but has more ZDDP and better HTHS numbers. My car is 90% street driven, but it also sees regular track use every couple of months. The Amsoil 5w-30 pumps very easy at cold temps & is safe for stop & go street use. It also gives me extra peace of mind knowing it has extra ZDDP & probably better base stocks over Mobil 1, along with a better HTHS rating. If I notice the oil temps getting too high at the track, I may switch to one of their 5w-40 formulas, like the Euro or the premium diesel.

I monitor my wear with UOA's at every oil change so I can keep tabs on this.
 

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wow, lots of good info. Anyone know anything about Redline?
Red Line uses a Group V, polyol ester, basestock, as compared to a Group IV, PAO basestock used in all AMSOIL fluids except their XL line which uses a Group III, highly hydroprocessed mineral oil basestock. Castrol and most other mainline synthetics use a Group III. Royal Purple doesn't specify what they use. Historically, Mobil 1 has used a Group IV PAO basestock, but recent analysis by guys on the oil forums indicate that they are now using a large percentage of Group III basestock in their oils. Mobil 1 has been very tight lipped about any change and their website doesn't provide much info.

I feel that knowing what basestock you are using is important because the basestock impacts performance in different ways. One of the significant areas is on absorbant material, such as seals. Esters, such as those used by Red Line causes seals to swell. PAO's cause them to shrink. The oil companies found that by adding a small portion of ester basestock to a predominantly PAO basestock results in a fluid with a vastly improved coefficient of friction and one that causes a very slight swelling of seals (helping prevent leaks).

Red Line's HTHS rating are high, but they don't use the same ASTM method so I didn't list them above. Based on virgin oil analysis I've seen on the oil forums, Red Line also doesn't appear to be complying with API SM limits (their zinc and phosphorus is above the API SM/ILSAC GF-4 limits). That may be good or bad depending on your perspective.

Back in 2003, I read several reports about Red Line that gave me pause and I obviously chose AMSOIL over the other options. Most of these reports were in tranny and diff applications. I felt more comfortable with the PAO basestock that AMSOIL uses.

That said, many of the guys I race against use Red Line in their Z06's and I'm not aware of any specific failures that any of them have attributed to Red Line.
:cheers:
 

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i know a little bit about the zinc deal,and that alot of people are using diesel oil because of that.it seems that the only people having problems with govt.mandated low or no zinc levels are those that have flat tappet camshafts.just about every car today has roller tappets,including our corvettes.
fwiw i use red line 5w30 in all of our cars except my prostreet big block and the wifes mercedes.20w50 and 10w40 redline in those.
 

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way to thick..

10w30
5w40
5w30

only weights I would run
 

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i know a little bit about the zinc deal,and that alot of people are using diesel oil because of that.
Keep in mind that the new CJ-4 diesel spec put similar, but less stringent limits on phosphorus as did the SM spec for automotive oils. The CJ-4 spec is 0.12% or 1200 ppm. There are still some diesel oils on the market, such as the AMSOIL Heavy Duty Diesel 5w30 that 4wheels uses, that are CI-4 plus and can have higher ZDDP levels. But again, this is somewhat brand dependent. Just because it is CI-4 plus vice CJ-4 doesn't mean it will have higher ZDDP, just that it can (and the AMSOIL HDD 5w30 does). AMSOIL makes a CJ-4 diesel 5w40 and intends to keep the CI-4 plus 5w30 (and 15w40) in production as long as there are pre-2007 diesels on the road... which obviously will be a while.
 
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