Very useful information, thanks a lot.

 

Would a larger oil cooler (assuming one exists) reduce the need for the 15-50 oil when tracking. Can a larger cooler keep the temps in check sufficiently, or are there other reasons for the 15-50 (such as a greater number of anti-wear additives as mentioned earlier)?

It seems that GM could have used a larger cooler and not required changing oils before and after a track day (which adds a couple hundred $$ or a couple hours of extra prep time - neither of which is insignificant to some of us).

I've used Mobil 1 10-30 in my 2003 Nissan 350Z with great results (both on and off track), but the engine is an older design and likely less stressed, so maybe it's a good match for the car. Would be nice to be able to get a couple track days out of an oil change, and not need to swap to a "street" oil between events. This recommendation and the brake "cooling rings" make me question exactly how ready for the track the C7 really is.

-T

 

Another option might be Mobil1 0W40 which according to a rep I spoke to at their booth at the PRI (Performance Racing Industry) show is one of their best oils, and which meets most of the European high performance standards from various manufacturers, including Mercedes, BMW, Porsche, VW/Audi. It is factory fill on the Nissan GT-R and on all Porsches I believe, including the GT3's. In my GT-R which I have been tracking without a hitch for 5 years, the factory fill of 0W40 is never changed for a higher viscosity even for track events, and Nissan has no requirement to go to a higher viscosity. I did oil analysis and it had no problems. Mobil1 0W40 is the only oil recommended for the GT-R, and this was confirmed in a video by the car's chief engineer (equivalent to TJ) at a track event in Australia, where he said the reason was its lack of sludge formation of 0W40 when it is run at the highest temperatures in the upper parts of the cylinder, which other oils cannot match. I think Porsche is the same, and it's 0W40 for both road and track.

Obviously 0W40 has a higher viscosity at 212F than does 5W30, but not as high as 15W50. It also has higher levels of zinc and phosphorus than 5W30 Mobil1 with a Dexos1 spec, but not as high as Mobil's 15W50. Good enough for Porsches and GT-R's, might be good enough for C7's. Note that Mobil1 5W30 with Dexos1 spec does not pass the high temperature/high shear test ACEA of A3/B3 like the 0W40 and 15W50 do.

Mobil1 Extended Performance 5W30 (Dexos1)
ZDDP levels (Phosphorus 800 PPM, Zinc 900 PPM) ACEA rating A1/B1 A5/B5

Mobil 1 0W40 (recommended for HT/HS or High temp/High Shear applications)
ZDDP levels (Phosphorus 1000 PPM, Zinc 1100 PPM) ACEA rating A3/B3 A3/B4

Mobil 1 15W50 (recommended for HT/HS or High temp/High Shear applications)
ZDDP levels (Phosphorus 1200 PPM, Zinc 1300 PPM) ACEA rating A3/B3

Here are the description of the ACEA ratings:
http://www.acea.be/images/uploads/pu..._LD_and_HD.pdf

A/B : gasoline and diesel engine oils

A1/B1 Oil intended for use in gasoline and car + light van diesel engines specifically designed to be capable of using low friction low viscosity oils with a High temperature / High shear rate viscosity of 2.6 to 3.5 mPa.s. These oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt.

A3/B3 Stable, stay-in-grade oil intended for use in high performance gasoline and car + light van diesel engines and/or for extended drain intervals where specified by the engine manufacturer, and/or for year-round use of low viscosity oils, and/or for severe operating conditions as defined by the engine manufacturer. High temperature / High shear rate viscosity of 3.5 mPa.s as a minimum.

A3/B4 Stable, stay-in-grade oil intended for use in high performance gasoline and direct injection diesel engines, but also suitable for applications described under A3/B3. High temperature / High shear rate viscosity of 3.5 mPa.s as a minimum.

A5/B5 Stable, stay-in-grade oil intended for use at extended drain intervals in high performance gasoline and car + light van diesel engines designed to be capable of using low friction low viscosity oils with a High temperature / High shear rate viscosity of 2.9 to 3.5 mPa.s. These oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt.

Note that Mobil1's 0W40 meets both A3/B3 and A3/B4, while their Dexos1 oil only meets A1/B1 spec, which is not as high for the HT/HS rating. 15W50 also meets A3/B3.

And you can buy large jugs of Mobil1 0W40 now at Walmart.

 

Don’t know why you’d think the 350Zs engine is less stressed than the Vettes? Would think the Z has a higher redline? Not ragging you, just think GM is taking measures to ensure reliability and limit warranty issues. Frankly I’m shocked that they accept tracking. Don

 

Great info and want to add one more data point. For the C6, in Europe, 40W was the recommended fill. Not sure what the Euro cars came with but 40W was the recommendation and lots of folks are loving the Mobil1 0W-40. It's what I will run when I get a C7.

 

As a quick heads-up, M1 5W-30 Extended also meets A3/B3 and A3/B4 spec, which is why I've switched over to it.

0W-40 will be considered 'out-of-specification' if you have a warranty claim, as far as I know.

 

Also, Euro Castrol (now known as Castrol Edge w/ SPT) meets A3/B3 and A3/B4 spec. Normal Castrol Edge (Synth) does not.

 

The 350Z redlines @ 6600 RPM, like the LT1, but displaces only .58 L/cylinder. The LT1 displaces .775 L/cylinder. I haven't run the piston and acceleration numbers to know for sure, but such a significantly larger displacement per cylinder indicates that there is either a larger stroke (higher speeds and accelerations) or larger bore (likely higher mass therefore greater force) than on the Z's engine.

Also, the LT1 has a higher compression ratio.

Again, this is just very rough seat-of-the-pants type estimates based on partial knowledge. would need to run the numbers based on bore/stroke/rod length to see how the stresses really compare. BMEP is likely a little higher on the Z's engine. Just thinking out loud really.

-T

 

Good points above. It's all about moving mass and compression ratio.

 

I think the answer is a qualified yes. Recognize I track (race) my 02 Z06, not a C7, but the general thoughts, and concerns are the same. My car did not come with an oil cooler at all. The company that prepped my car and most of those that I raced against when I started racing in 2003 all used Mobil 1 15w50, even with the aftermarket oil coolers we use. I lost a motor my first year.

Switched to AMSOIL the following year but stayed with 50 grade, then dropped to 40 grade later that year. In 2007 I dropped to 30 grade and have been using it since.

At the track with my external oil cooler and aftermarket Ron Davis radiator, my oil temps are 245-255F (stock LS6 bearings) at almost every track I've raced at and the external air temp doesn't change it much. At those temps, I'm comfortable with the AMSOIL Dominator Racing 10w30 I use (zinc 1575 ppm, phosphorus 1474 ppm).

For those that track and street drive their cars, its harder. I drove my car on the street many years ago when I still had it licensed and insured and I couldn't get my oil temp over about 150F - too much cooling for the street. A lot of guys with similar setups to mine that were dual street/track cars made covers for their oil cooler for the street. Others put valves in the cooler lines to isolate it.

So, yes I think a 40 grade or 30 grade is viable if you can keep your oil temps in check... and assuming you use an oil with the proper additives. This oil will not be one that meets API SN or dexos1 specs those. Tough call for C7 owners with cars under warranty.

I think the AMSOIL Z-ROD 10w30 I linked in post #31 above is an example of a 30 grade with the proper additives and as I mentioned, a lot of C5 owners use that oil as a dual use street/track oil. Note that it doesn't meet current specs for about anything due to its very high ZDDP levels.

 

i just posted a thread on the general discussion forum. maybe it belongs here. seems related to this post, so here goes.

the gist: new c& Z51--40 miles. oil overfull. checked properly. oil when cold, [25 degrees in the garage], drips off the dipstick almost like water.

anyone else experience any of this?

 

So what ever happened here? I'm curious.

 

Gents if you ever need any AMSOil let me know….

 

Or if you want to test your oil as well I can send it off and get you a reading. I would highly suggest a top tier oil for your car the hype of Mobil 1 is great and all but testing doesn't lie and the only way to find out what your car is leaving for a byproduct in your oil or what the chemical makeup is after extended drains is to send it off.

My C5Z and C6Z have all ran AMSOil Signature for the street, with phenomenal outcomes.

 

M1 Extended tests favorably long-term, but Amsoil gives generally better results.

Do keep in mind that Amsoil is still not listed on the official 'dexos1' vendor table.

Reference: http://www.centerforqa.com/gm/dexos1-brands

 

I will be at PBIR for five 20 min sessions. I still have the original oil in the engine(3,500 miles)
which came from GM (dextros). Do you think it's OK to change to 5W 30 Mobile 1
prior to the track day, as long as I take it fairly easy? Temps for the day will be in the high 60 to 70s.

I have a 350 mile drive there and back also.

 

Absolutely get the stock oil out of there first.

I would think (just an opinion) that the 5W30 M1 (Extended) would give you enough protection for those runs. However, it may be worth the extra money to give some peace of mind.

You could also thicken your mix before the race and thin it back out (saves a bit of money). Drop 2 qts of 15w-50 and 8 qts of 5w-30, then drain off a few and re-add 2 qts of 5w-30 afterwards.

It's really up to how comfortable you feel with any of it. Remember that the manual does tell you to switch over to 15w-50, but it also tells you to install the brake coolers, etc. before tracking.

 

concensus--or at least my take on it was it is no big deal.
i have 500 miles on the car including a 300 mile trip to VA. no issues.
so i am just going on in la lal land like there is nothing to see here.

it's been so cold i can't drive it to see what, if anything changes.

very sorry to bother everyone with a non-problem [??]. if anything changes, if global warming ever kicks in, i'll keep you all informed.

 

No bother - always good to know what crops up!

 

And.........to change to high temp brake fluid. Yes, I am aware of the brake rings too!

Thank you for your input. This track day gonna' cost a lot more than the $299 track fee. I thought I would just show up and learn something new.
I am learning something new alright. ...........gotta pay to play!