Street/Track Corvette LS7 - New Motor !

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Dirty_Howie

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Can I please get some advise. I blew up my last motor and will shortly have a brand new one (Stock OEM LS7). The last motor had 87K miles (3.5 years old). The car is a daily driver (2 cold starts every day). I also take it to HPDE single day track events about 10 times a year. The car lives in southern california.

There is a body of thought that LS7 motors are failing due to broken exhaust valves. And this is caused by a premature wearing of the valve guides. Which in turn leads to fatigue in the valve and the valve head breaks. So a better suited oil might address this problem if it can better lubricate the valve stem and guide. Not sure if ZDDP helps with this particular issue.

I used Mobil1 5w30 on last motor and am considering changing.

I have heard from other sources that you want to stick with a 5w or 0w for a daily driven car. It is also typically suggested to run a 40w for the track. And since Mobil1 0w40 has higher ZDDP than the 0w30 and is actually put in the same motor/car in Europe by GM this is the most likely candidate.

But I have read hear before that any 0w40 will break down quicker than a 10w30. Also some believe that you should never have over w30 in these engines due to clearance tollerances. So I am looking at something like the Amsoil Z-Rod (or a Redline similar oil) with its higher ZDDP than the Mobil1.

I am torn between the different opinions I hear and am asking for advise.

Thanks

DH
 
With a machine like that, I'd use nothing but the best; Redline or the Amsoil Z-rod. If oil temps are a concern when it's tracked, I'd bump up to a 40 weight minimum, but the 30 weights in those 2 oils are on the thick side of 30 weight.
 
A common recommendation is Redline 5W30... which, per the specs, is closer to a mainstream synthetic 5W40.

Being that it lives in a mild climate and sees a fair amount of track use, Redline 5W40 may not be a bad option either. As far as "clearances" making a w40 unsuitable, do you think BMW assembles "loose" engines for their M cars? They recommend 10w60.
 
I have an LS7 (Not Stock) in my Tatum blackwidow ( Sand car ). I have been very pleased with Red Line 5-30 in it. I mean This engine gets abused with high load spinning paddles and extreme heat. You may want to give the Red line a try. I bet M1 0-40 would work well to
 
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Hey DH. Here is my 2 cents worth. Increasing the ZDDP and Moly content that Redline offers is a step in the right direction. Both function as a boundry layer lubricant and in a 7000 RPM 427 V8 used on a racing track thats going to come in handy. Whether that will provide any lubrication at the exhaust valve-valve guide interface where these failures occur, I don't know but it couldn't hurt. My vote is for the RL 10W-40. As soon as you get out of warranty; I would remove the cats and save them for reinstallation when you need to start smogging the car biannually; the track use and the high ZDDP will kill them off pretty quickly(ask me how I know) and its a $1500 adventure on a car like yours. See you out there soon. Sidney
 
Originally Posted By: JosephHarmon
Do you monitor the oil temps realtime?
Have you investigated the root cause of the failure?


I agree....oil temps and pressure?

Root cause? Especially now that you are putting in a new engine....is there an aftermarket fix for this since its a known issue? Somebody usually comes up with a fix.....oil would just be a band aid..IMHO.
 
Originally Posted By: Drew99GT
With a machine like that, I'd use nothing but the best; Redline or the Amsoil Z-rod. If oil temps are a concern when it's tracked, I'd bump up to a 40 weight minimum, but the 30 weights in those 2 oils are on the thick side of 30 weight.


Okay thats good to know. I didn't know there was THICK 30 weight. Is Mobil1 considered a THIN 30 weight?

DH
 
Originally Posted By: JosephHarmon
Do you monitor the oil temps realtime?
Have you investigated the root cause of the failure?


Yes I do monitor oil temps. I have got into the 290's on occasion. But mostly 260-280 range.

I will not know what actually happened to my motor as it is being shipped back to GM. Wish we could tear it down. But others have had similar failures and it is usually a valve failure.

DH
 
Originally Posted By: MrHorspwer
A common recommendation is Redline 5W30... which, per the specs, is closer to a mainstream synthetic 5W40.

Being that it lives in a mild climate and sees a fair amount of track use, Redline 5W40 may not be a bad option either. As far as "clearances" making a w40 unsuitable, do you think BMW assembles "loose" engines for their M cars? They recommend 10w60.


Don't know much about engine tolerances and suitability of different oils. Thats why I am asking.
 
Originally Posted By: Smokefan1977
I have an LS7 (Not Stock) in my Tatum blackwidow ( Sand car ). I have been very pleased with Red Line 5-30 in it. I mean This engine gets abused with high load spinning paddles and extreme heat. You may want to give the Red line a try. I bet M1 0-40 would work well to


I assume the Redline has high ZDDP like the Amsoil. What is the comparison between the two??

DH
 
Originally Posted By: sidney004
Hey DH. Here is my 2 cents worth. Increasing the ZDDP and Moly content that Redline offers is a step in the right direction. Both function as a boundry layer lubricant and in a 7000 RPM 427 V8 used on a racing track thats going to come in handy. Whether that will provide any lubrication at the exhaust valve-valve guide interface where these failures occur, I don't know but it couldn't hurt. My vote is for the RL 10W-40. As soon as you get out of warranty; I would remove the cats and save them for reinstallation when you need to start smogging the car biannually; the track use and the high ZDDP will kill them off pretty quickly(ask me how I know) and its a $1500 adventure on a car like yours. See you out there soon. Sidney


Thanks for the tip Sid. I new ZDDP wasn't good for cats but didn't know it ruined them quickly and definitely didn't know it was $1500 to replace. But how much is it to remove them?? My concern on a 10w40 is that it is too thick for daily use. Its my DD and therefore gets at least 2 cold starts per day. And according to some that can cause more wear than track use !!

And yes ...... hope to see you out there soon.

DH
 
Originally Posted By: mcrn
Originally Posted By: JosephHarmon
Do you monitor the oil temps realtime?
Have you investigated the root cause of the failure?


I agree....oil temps and pressure?

Root cause? Especially now that you are putting in a new engine....is there an aftermarket fix for this since its a known issue? Somebody usually comes up with a fix.....oil would just be a band aid..IMHO.


There isn't universal agreement. Some say a good valve job and bronse valve guides. Others say changing the valves themselves to SS along with different springs and bronse guides.
 
Originally Posted By: JosephHarmon
That's expensive parts changing to be dismissing knowing why.

In all likelihood the oil itself had nothing to do with it.


This may be very true. But since this motor will not be under warranty I can use whatever oil I like. So I would like to use the best oil available for my usage and remove the oil itself as a possible source of the problem.
 
While both are fine products:

Redline Street Products specialty = Street/Track Car

Amsoil specialty = Extended Drain

At least in my mind.

At the very least choose an oil with an HTHS over 3.6 which the M1 5W30 doesnt. While its apples and oranges my 2011 5.0L Mustang (which specs 2.6 HTHS 5W20) gets 4.6 HTHS 5W40 on the track.

Mobil 1 5W30 = 3.1
Redline 5W20 = 3.3
Redline 5W30 = 3.8
Redline 0W40 = 4.0
Redline 5W40 = 4.6
Redline 10W40 = 4.7
Redline 15W50 = 5.8

PS My personal opinion is the valves should be changed and the guides checked on a routine basis if you are going to continue to track the car.
 
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I wonder how much additional ZDP would help in an engine like this? Redline is a great suggestion. You could even try their 5w20. If you decide to stay with Mobil 1, the 0w40 is probably a good choice although the new SN 5w30 maybe fine also.
 
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