0W40?

[Dynomite]

Originally Posted by Hib Halverson

Starting in 2019, GM changed to a 0W40 engine oil for all Corvette engines except the LT6 which uses a 5W50.

Has anyone tried a 0W40 in the first generation LT5?

I would think that the same two major advantages?1) oil gets to bearings more quickly on cold starts and 2) better thermal stability during aggressive engine operation?that GM gained with using a 0W40 in the 2G LT5 and the LT2 woulid be useful in the original LT5.

What is the maximum cam pressure on the lifter for an LT5 engine?

Going from a 4,000 rpm to over a 7,000 rpm engine is a BIG factor in Cam Pressure and wear.

I also know from an experience that the cam tips are not parallel with the Lifter surface on the LT5 engine. (Cam Tip being the high "edge" of the Cam that gives the Lifter maximum compression).

An Aberration in Cam Wear

The localized pressure on the lifter must be very difficult to determine in that case....

The Cam Wear on the tips can be seen on the Cams pictured below.



I assume the cam tip being tilted and off center on the Lifter surface keeps the lifter rotating. The lifter rotating under the cam acts like a rolling intersection (not purely frictional). [B]The surface of the Lifter is moving vertically and horizontaly as the Cam Tip slides/rolls across the Lifter. (It is hard to imagine this happening up to 60 times a second).

Redline (maximum safe operational engine speed) is a BIG factor on ZDDP issues.....

Redline for L98 is 5,500 rpm.
Redline for LT5 is 7,200 rpm.

Mobile-1 for racing engines (high rpm) shows much higher ZDDP

Originally Posted by spork2367

https://www.mobil.com/lubricants/-/m...pecs-guide.pdf

Notice the zinc and phosphorus content on the racing oils...

Post 294 - Camshaft Abnormal Wear

A little more detail on Oil/Zinc/Cam Wear from Hib Halverson........

Oil/Zinc/Cam Wear Part 1

Oil/Zinc/Cam Wear Part 2

[tiegsd]

Originally Posted by Dynomite

What is the maximum cam pressure on the lifter for an LT5 engine?
Going from a 4,000 rpm to over a 7,000 rpm engine is a BIG factor in Cam Pressure and wear.

I also know from an experience that the cam tips are not parallel with the Lifter surface on the LT5 engine. (Cam Tip being the high "edge" of the Cam that gives the Lifter maximum compression).

An Aberation in Cam Wear

The localized pressure on the lifter must be very difficult to determine in that case....

The Cam Wear on the tips can be seen on the Cams pictured below.



I assume the cam tip being tilted and off center on the Lifter surface keeps the lifter rotating. The lifter rotating under the cam acts like a rolling intersection (not purely frictional). [B]The surface of the Lifter is moving vertically and horizontaly as the Cam Tip slides/rolls across the Lifter. (It is hard to imagine this happening up to 60 times a second).

Post 294 - Camshaft Abnormal Wear

A little more detail on Oil/Zinc/Cam Wear from Hib Halverson........

Oil/Zinc/Cam Wear Part 1

Oil/Zinc/Cam Wear Part 2

Thanks for the pointers to these articles. I imagine this is about as detailed a history as you are going to find anywhere on the topic.



Early in the Part 1 article, it is stated that the LT-5 having flat tappets is "... only peripherally related to this wear issue, because it had overhead cams and direct acting, bucket-type flat tappets." It would seem to imply that the LT-5 operating conditions are less severe, but I may be reading to much into that statement.


I'd be interested to know what drove the choice of ZDDP content for the LT-5 and whether it's valve train design is a more or less (or neither) severe case in terms of valve train loading and wear compared to older flat tappet OHV engine designs.


Also, if anyone knows, whether the recommended oil for the LT-5 changed at all between the different model years?

[spork2367]

Originally Posted by tiegsd

I'd be interested to know what drove the choice of ZDDP content for the LT-5 and whether it's valve train design is a more or less (or neither) severe case in terms of valve train loading and wear compared to older flat tappet OHV engine designs.

It's generally accepted to be less severe than high performance pushrod engines. It's probably equal to or more severe than low performance pushrod engines.

However, emissions equipment life drove the ZDDP content for all API approved engine oils. Zinc deposits can reduce catalytic converter life. Interestingly, I haven't found any great articles on how much zinc reduces the catalyst life by how much.