May be of interest to Mobil 1 users.

[DRM500RUBYZR-1]

It's soon to be Friday night, and snowy for some of us.
Grab a good bottle of Cabernet, Scotch, or a twelve pack,
and spend some time reading this:


https://www.corvetteforum.com/forums...-your-lt5.html


Having re- read it, I may just go back to my trusty old Mobil-1.


I neither endorse, nor condemn any of the responses in the thread, even mine.
Good Reading, but focus on post #22


Marty

[lfalzarano]

From Marc’s write-up, Amsoil AMO 10W-40 is the best to keep your LT5 running for years to come. Don’t take a chance and cheap out on your car.


Sent from my iPhone using ZR-1 Net Registry

[Ccmano]

Originally Posted by DRM500RUBYZR-1

It's soon to be Friday night, and snowy for some of us.
Grab a good bottle of Cabernet, Scotch, or a twelve pack,
and spend some time reading this:


https://www.corvetteforum.com/forums...-your-lt5.html


Having re- read it, I may just go back to my trusty old Mobil-1.


I neither endorse, nor condemn any of the responses in the thread, even mine.
Good Reading, but focus on post #22


Marty

Great find Marty. Everyone should read post #22 in that thread. My personal opinion is that for the LT5 the zddp Issue is overblown. Especially in light of the fact that there is no imperical evidence that LT5 motors have been damaged from current zddp levels. The 181k mile Z in my garage (a one owner dealer serviced car) is evidence that regular maintenance with a quality oil, probably Mobile One, is what these engines need for a long trouble free mechanical life.
H

[XfireZ51]

Let’s say I know a certain Greek w re-ground cams that doesn’t add ZDDP.
The seat pressure for our valves vs pushrod motors is very different.

[SBAquaLT5]

Didn't mean to hijack the thread.. It's great reading the thoughtful comments from here! Everyone is well read and cares about their car... I took the good suggestion of having a glass of wine, but it's snowing ash here instead of the water stuff..

My 2 Cents

The low seat pressure on the valve followers is a legitimate argument, and so is the minimal damage from regular synthetic.
Those who've run Mobil1 for years have probably only subjected the engines to reduced ZDDP recently as the blends have become less and less. The air cooled Porsche community also shares the same concerns and most run VR-1 or Brad Penn. I wouldn't expect to visually see a difference in the cam lobes from 900 vs 1200 ppm for (tens)thousands of miles on our cars, but I always subscribe to the "ounce of prevention" side of things.

Lately I'm more curious as to why 10w40 is suggested over the 5w30. Historically thicker oil is used in severe conditions due to reduced viscosity at high temperatures, especially true of old petroleum oils. However our cars hold 9 qrts of fancy synthetic oil and have oil coolers. They look to be pretty stable on oil temp. I could only guess more shock protection for timing chains, or machine tolerances/shear protection...? I use Mobil1 in a lot of vehicles too

[Paul Workman]

Originally Posted by XfireZ51

Oh great! I just switched to it.
However, I am noticing an appreciable reduction in oil consumption.

Ummm...was the consumption down due to a change of oil brand or the repair of that broken ring do you think?

(Had to ask!)

[XfireZ51]

Originally Posted by Paul Workman

Ummm...was the consumption down due to a change of oil brand or the repair of that broken ring do you think?

(Had to ask!)

Paul,

When the motor was first put back together, it was filled w my regular oil
Castrol GTX DIESEL because of its ZDDP content. However, Pete strongly suggested I swap that out to a synthetic, so I decided on Mobil1 High Mileage
based on recommendations here.
Checking oil after 4-500miles of driving, the consumption appears to have slowed down noticeably. Down about 1/2 qt.

[Dynomite]

Originally Posted by Ccmano

While low zddp levels in modern oil is a known and verified source of cam and flat tapped wear in older design engines, has there ever been a verified case where this happened on an LT5 engine?

I’ve been around the LT5 engine for going on 10 years now and I can’t honestly say I have ever heard of one. Has anyone ever asked Haibeck or Cory Henderson if they have run across one.

Just curious....
H

Yes On a Low Mileage 1990

Camshaft Wear Aberation on a Low Mileage 1990 ZR-1

[Ccmano]

Originally Posted by Dynomite

Yes On a Low Mileage 1990

Interesting... This is one of these questions that will never truly be answered. Did this camshaft fail because of the Zddp issue, was it a defective camshaft, was it because of the infamous cold start procedure at the plant in 90’ where cold new engines were reved to redline at startup or simply owner neglect.
We will never know.

Now, show me a dozen of these accross multiple model years and I might be convinced.
H

[Dynomite]

Originally Posted by Ccmano

Interesting... This is one of these questions that will never truly be answered. Did this camshaft fail because of the Zddp issue, was it a defective camshaft, was it because of the infamous cold start procedure at the plant in 90’ where cold new engines were reved to redline at startup or simply owner neglect.
We will never know.

Now, show me a dozen of these accross multiple model years and I might be convinced.
H

Well....Now you have heard of one situation (other situations are mentioned in Camshaft Wear Abberation on a Low Mileage 1990 ZR-1)
Very Very Few ZR-1 owners ever look under the Cam Covers even though that is possible without removing the engine. Even less of ZR-1 owners remove the LT5. Marc Prolly has the greatest experience looking at Camshafts as he posted in this thread... Camshaft Wear Abberation on a Low Mileage 1990 ZR-1

Now....Back to Sanity and a great follower of Marc Haibeck.
I have five ZR-1s which ALL get the same Top End Reconditioning and ALL have the Same Fluid Changes.......and ALL questions I have had for Marc Haibeck and advice by Marc are incorporated in ALL ZR-Is
I repeat myself here again

I use Mobile 1 engine oil in everything else except the ZR-1s just like George

I use Mobile 1 Oil Filter and Mobile 1 Differential Fluid in the ZR-1s, PERIOD

I use Amsoil 10W-40 in the LT5 engine.
I use Castrol 10W-60 in the ZF S6-40 (Black Label or Blue Label) Transmission.

See What Fluids to use in the ZR-1


.........