I only have a C7 on order but have been reading the owner’s manual on line. They specify 15W-50 Mobil 1 for those who compete with Z51 C7s. Logic says the only reason for that is superior protection, particularly since the dry sump system already gives the car 3.3qts more oil which helps keep the oil temps down. Don

 

While I'm not sure I agree with it (after the fiasco of the wrong oil capacity numbers, failed fluid levels, etc.), here is the section Don is looking at:

 

15-50 should probably just be done on cars here in Phoenix around April/May when it will hit the 90's and low 100's.

 

For more GM info about DEXOS:

http://www.gmdexos.com/

 

The following Valvoline products will meet all performance requirements of the GM dexos 1 specification and therefore in GM’s terminology will be GM Dexos 1 equivalent oils:





Valvoline SynPower Full Synthetic SAE 5w30 For GM dexos 1


Valvoline SynPower Full Synthetic SAE 5w20 For GM dexos 1


Valvoline DuraBlend Synthetic Blend SAE 5w30 For GM dexos 1


Valvoline MaxLife Synthetic Blend SAE 5w30 For GM dexos 1


Valvoline SynPower Full Synthetic SAE 5w30 MST For GM dexos 2





Your vehicle will most likely operate at it's best using Valvoline SYNPower 5w30. Check your owners manual for the correct oil viscosity

 

I received the results of our oil analysis last week.

While I've been asked not to disclose any info, suffice to say that it's not a bad idea to change your oil after the first 500 miles...

And for those of you who are really into oil, look into oil analysis at regular intervals. It's a cheap insurance policy and lets you keep a good eye on the vehicle.

 

Also, probably a no-brainer, but I just double checked my two bolts here.

Both front and mid oil bolts on the Z51 are the M12x1.75 (M12 x 1.75mm) variety - same as with the C6 I believe.

I'm ordering magnetic ones right now.

 

I would agree about the Start Up protection. That is the most vulnerable time for any engine and theses days mfgs look at the oil's ability to lubricate during cold startup temps.

I saw some figures on this a few years back and Mobil One ranked number 2 or 3 of the best but I can't remember the others. Sorry.

 

I believe Amsoil was one of the top 3, as well.

 

Keep in mind that dexos1 is a spec for GM automotive oil (diesel is dexos2) and that GM sells their own proprietary brand which meets this spec obviously. It is commonly recognized online that this spec can be met by a semi-synthetic though I can't quote an authoritative source for that.

You can get many high quality synthetics that meet this spec including AMSOIL's full line of street synthetics:
AMSOIL Signature Series 100% Synthetic 5w30 (Product Code ASLQT)
AMSOIL XL Synthetic 5w30 (Product Code XLFQT)
AMSOIL OE Synthetic 5w30 (Product Code OEFQT)

This is not correct. Extended life oils like AMSOIL's Signature Series and Mobil 1 Extended Life are designed for extended drain intervals (e.g. up to 15k miles for Mobil 1 Extended Life). To meet these extended drain intervals they generally have higher quality basestocks than OE drain interval oils and they have significantly higher levels of detergents and dispersants.

High Mileage oils are for high mileage cars and they generally have additives that expand seals to help prevent leaks in older cars. This is more likely what Jim is referring to.

High Mileage oils are somewhat of a misnomer in my opinion. There is no definition of what is or isn't high mileage. Rather, I'd think of them as viable for cars out of warranty. High Mileage oils allow the oil companies to market oils that don't meet current API SN specs (or dexos1). While many differences to the oil specifications have occurred over the last decade or so, one of the primary ones was the gradual limitation on phosphorus.

Phosphorus, along with zinc, in a compound called ZDDP, or or zinc dialkyl dithio phosphate, forms an oil's primary anti-wear additive. Unfortunately, phosphorus slowly poisons the cats and prevents the catalytic exchange that allows them to function properly. To ensure auto companies could meet the EPA's 100k+ emissions requirements, the API has slowly been dropping the limit on phosphorus.

When I bought and started tracking my 02 Z06, most top street oils had ~1200 ppm zinc and phosphorus. The current API SN spec has the band 600-800 ppm phosphorus.

So, any oil labeled to meet the current API SN spec will be limited to 800 ppm max phosphorus. This impacts how well it will be able to perform in anti-wear, such as might be seen in your bearings under heavy load.

High Mileage oils, or other oils that aren't labeled to meet current specs (API SN and dexos1) can bypass this limit. Mobil 1 5w30 has 900 ppm zinc, 800 ppm phosphorus. Mobil 1 High Mileage 5w30 has 1100 ppm zinc, 900 ppm phosphorus.

Viscosity grades higher than 30 grade also allow the oil companies to bypass this limit on phosphorus. Though GM doesn't state it in the owner's manual, in addition to the increase in viscosity of the Mobil 1 15w50, it also has a lot more ZDDP - 1300 ppm zinc, 1200 ppm phosphorus. I strongly believe that this higher ZDDP is needed for the track.

There are 30 grade options with higher ZDDP. I use this in my stock LS6 at the track:
AMSOIL Dominator Synthetic 10w30 Racing Motor Oil (Product Code RD30QT)
(zinc – 1575 ppm, phosphorus 1474 ppm)

A lot of the C5 owners who both street and track their cars use this:
AMSOIL Z-ROD 10w30 Synthetic Motor Oil (Product Code ZRTQT)
(zinc – 1440 ppm, phosphorus 1320 ppm)

The Z-ROD is similar to Mobil 1 High Mileage in concept (bypassing current API SN and dexos1 specs), but has a higher viscosity (near the top of the 30 grade band - almost a 40 grade) and has more ZDDP - more than Mobil 1 15w50. It is very similar to AMSOIL's Dominator Racing oil that I use, but has sufficient detergent/dispersant for 3-5k miles (or one year whichever first) oil change intervals whereas I change my racing oil about every 500 track miles.

 

I was going to ask which one of my co-workers you were, but I just saw the banner at the bottom.

Spot-on information.

Run an analysis (send it to TestOil since they have ours on file for comparison) on the blend shipped from the factory in the C7... You'll find it interesting.

 

Ok so basically you have me convinced to change the oil at 500 miles along with installing a magnetic plug.

You should share your findings about the oil test that would be some interesting info to know

 

It does for track time on the Z51.....

 

As I said before, I was asked by two parties to not disclose the information for various reasons (one of the worries being contamination of the original test).

We were able to run two independent tests with independent labs to ensure no contamination (I work for an oil company, and we know what we're doing with collection procedures).

...... ......

However, against my better judgement, I've edited the crap out of this while still leaving in enough to work from. I'm pretty sure any oil people here can see some scary stuff for a 500-mile change. Please don't re-post this.



Click on the picture to make it larger if you need to.

 

Interesting oil analysis. Hopefully the out of spec levels will be closer to normwl if you have it analyzed after the next change. So much for leaving the original oil in until the DIC says it needs to be changed. Based on thse numbers I'd change it early too.

 

Thanks for posting that. I will be getting my new car in a few months and had every intention of running it 7-8k miles before the first change. Not anymore !!

 

If you want to run it for the first 500 miles or so, that will get the break-in contaminants out of there.

My thoughts on the silicon are having something to do with casting contamination... Just a thought - no evidence, etc.

It's an expensive change (10qt + filter ~ $100) to say the least, but it's a chance to put magnetic plugs (in this design they grab before the sludge goes to the pump) in and get the blend out of there.

If you're really into oil changes for tracking, etc. you can put one of these on! I'd do this if I got free (or cheap) oil, but alas, I pay almost $9/qt for mine like the rest of us...

 

So here is a question: I know you're supposed to run 15W-50 for track events, but is there any negative to using it all the time?

 

Yes, do not run 15W-50 for anything other than heavy track events, and drain it immediately following.

Never run anything other than 5W-30 in these engines full-time (with the exception of a few 0W-40s that are closer to 5W-30, but that's for another topic)...

 

The downsides are increased wear at start up due to the much higher viscosity (particularly where it is cold), and increased pumping losses (less net HP and lower mpg) at normal operating temp.

At a nominal oil temp of 212F, Mobil 1 5w30 has a viscosity of 11 cSt. Mobil 1 15w50 viscosity at 212F is 18 cSt - an increase of over 60%. It's worse at lower temps. The main benefit of the 50 grade for the track is that the oil gets so hot the 30 grade viscosity drops too low to provide proper fluid film protection to the bearings. Somewhere around 260F or so, the 15w50 will have the same viscosity the 5w30 has at 212F.