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15w-50 is recommended for track use for both the C7 and C8. Stands to reason that the new "supercar" 5w-50 would be perfectly suitable as well. 50w vs 50w and the super car being ostensibly more 'modern'. I ran the 0w-40 in both cars over the winter and then switched to 5w-50 for the hot months. According to the PDR data oil temps in the C8 were actually marginally lower and more consistent even in higher ambient temps. The upside is I'm no longer seeing hot idle pressure at 21-22psi after a session. This probably doesn't matter either way given the variable oil pump, but in our heat and humidity I'll take the additional viscosity. Anecdotal since my C7 doesn't have PDR but oil temps seem to be a bit lower vs the 40 as well.
One major concern I'd have would be possible warranty challenges. After all, this is not a recommended oil for this use case, and it may be blamed if an engine bearing gives up. As soon as GM starts being OK with it, I'd be onboard, too : )
In my experience, thicker oil always 'increases' oil temps due to increased friction; I'm surprised about your experience.
Re: trying as stock, I like that idea, but I always think Z51s, especially ones with no MRC like Miatas: very soft sprung, and not ready for any high traction tire. On the top of that, you also cook brakes. As such, I've decided to put in the goodies even before trying it as stock this time. I did drive the Z06 quite a bit in stock form (but with race pads, etc. of course), and it was great! In fact, with Z07 package, it was very very close to what aftermarket stuff can muster.
I've been using my left foot for braking on all our cars since I bought this car, and I'm still a bit more harsh than I used to be using my right foot; old habits die hard! In a panic scenario, I still slam the brakes harder than I should (had a few cases when someone cut into my lane in traffic, etc.). Anyway, I fear it will be a slow curve to get back up to speed at the track with this new rear engine setup, as well as left foot braking, etc.
Yeah, Corvettes are always slower on hotter days, except if you can cheat like @Nabush can do with E85 : ))) I plan to leave the engine bone stock, especially considering the very tight tuning it needs to work flawlessly with the transmission to prolong its life, and I don't really want to touch that.
Is 5W-50 even recommended for these engines? I thought I saw the recommendation only for the Z06 (LT6).
The 15w50 is in the track prep guide but a misprint/ carryover from c7. The z06 runs 5w50 not 15w50 so makes zero sense in modern times to recommend 15w50 that isn't dexos when 5w50 that is dexos exists.
The 0w40 esp X3 dexos 2 has a 3.8 ht/hs compared to our 0w40 supercar 3.5. Ravenol RUP 5w40 is 3.9 and dexos 2. Motul 300v 0w40 is 3.9. m1 5w50 supercar is around 4.4.
“GM engineers mentioned they've used hardest rubber they could use on the Z06 control arms compared to Stingray to reduce deflection with higher traction tires and suspension. If it's similar to how C7 T1 kit's control arms were compared to regular, they might be as much as 500% stiffer. With that, I think they might provide an excellent compromise; not as good as monoballs, but zero noise, zero vibration.”
It is clear that HTHS will be better with the thicker oil. That said, for a platform known to have lost quite a few engines and transmissions that were lost at the track, it's a tall order to just use a different oil and take the liability risk.
I don't think 15W-50 is a typo. After all, LT1, LT4, LT5 were certified for it (for track use), and LT2 is just an updated LT1. In any case, I'd never use it, since these cats clog, and they become a nuisance when they do, sipping power without you knowing, and finally cracking the headers, causing downtime.
I think we'll have different opinions on this, but 0W-40 is 'good enough' in my opinion, and I'll stick to it until GM approves 5W-50 as well. I've always had excellent wear results with 0W-40 ESP on C7 used on both LT1 and LT4.
Yeah Cup cars have been using 0w40 forever. I just assumed you didn't care about the warranty lol.
And the 15w50 is a misprint as its listed as applying to both the z06 and stingray. No way you would drain 5w50 dexos R from a stingray and put in non dexos 15w50.
Then later the track prep guide says to put back in a dexos 1 oil. That's way outdated and another misprint lol
One major concern I'd have would be possible warranty challenges. After all, this is not a recommended oil for this use case, and it may be blamed if an engine bearing gives up. As soon as GM starts being OK with it, I'd be onboard, too : )
In my experience, thicker oil always 'increases' oil temps due to increased friction; I'm surprised about your experience.
They're both Dexos R (whereas the 'approved' 15w-50 isn't) so I'm not terribly concerned, but I understand. It's a bit ironic the older, lower certified and half the price oil wouldn't be issue but the modern iteration would be. FAFO I guess.
As far as the temps, I am happily surprised as well but it's on avg 5° cooler lap to lap. I'm not touting that, just an observation. At 250° the viscosity difference between 40 and 50 is likely negligible.
15w-50 is recommended for track use for both the C7 and C8. Stands to reason that the new "supercar" 5w-50 would be perfectly suitable as well. 50w vs 50w and the super car being ostensibly more 'modern'. I ran the 0w-40 in both cars over the winter and then switched to 5w-50 for the hot months. According to the PDR data oil temps in the C8 were actually marginally lower and more consistent even in higher ambient temps. The upside is I'm no longer seeing hot idle pressure at 21-22psi after a session. This probably doesn't matter either way given the variable oil pump, but in our heat and humidity I'll take the additional viscosity. Anecdotal since my C7 doesn't have PDR but oil temps seem to be a bit lower vs the 40 as well.
I thought the MCS rates are 5x oem rather than 4x. Regardless, it still rides great on the street and is excellent on track. The balance is great with 275 on 10” and 325 on 12”, and a hoot to drive with the electronics off! When the tires are cooked it slides about as well as my M3 did, too.
I thought the MCS rates are 5x oem rather than 4x. Regardless, it still rides great on the street and is excellent on track. The balance is great with 275 on 10” and 325 on 12”, and a hoot to drive with the electronics off! When the tires are cooked it slides about as well as my M3 did, too.
Yes, you're right; I think OEM is around 40 / 47 N/mm Front/Rear, so it's about 4.5-5x.
No rubbing. Lowered about 3/4. -3.5 camber F&R, but the camber doesn’t allow for more clearance in my case. Stiffer springs help a good bit also. Offsets could go +5 more out F&R. I have about 4mm brake clearance.
No rubbing. Lowered about 3/4. -3.5 camber F&R, but the camber doesn’t allow for more clearance in my case. Stiffer springs help a good bit also. Offsets could go +5 more out F&R. I have about 4mm brake clearance.
@X25 did you happen to see if those APEX VS-5RS will clear the stock OEM brake calipers?
Any rubbing with the 295 and 345 tires?
Originally Posted by SPOHN
For reference I have
19x10 +45 295/30
19x12 +52 345/30
No rubbing. Lowered about 3/4. -3.5 camber F&R, but the camber doesn’t allow for more clearance in my case. Stiffer springs help a good bit also. Offsets could go +5 more out F&R. I have about 4mm brake clearance.
I am yet to try the car, so not sure about rubbing, but they seem to fine for now.
OEM wheels did not clear 9668 AP calipers with (25mm) thick pads at all. They were way off. APEX 18x10 ET42 wheels were able to clear the front brakes by a few mm. BC Forged 18x10.5 ET52 wheels do clear the AP brakes very comfortably. In light of these, APEX wheels should very easily clear the OEM brakes, both by barrel and by the spokes. I think they state it somewhere, too.
@X25 did you happen to see if those APEX VS-5RS will clear the stock OEM brake calipers?
Any rubbing with the 295 and 345 tires?
I'm running: Front: 18x10" ET42//Rear: 19x11.5” ET48 but 275/325. Per their fitment guide you'll get some rubbing up front with a 295 at full lock. I've experienced a tiny bit of contact with a 275, just enough to leave a light witness mark.
Looking forward to trying out 315s up front!! That will be a big test, and it's also the reason why I got custom BC Forged 18x10.5 wheels made to try that out. I was able to get this working on C7 Z51 with coilovers, so fingers crossed : )
