Cam lobe wear using Rotella T6

[Trav]

Quote:
What is the breakin mainly for, the journals or the lobes?


The lobes, the cam journal caps usually have no wear issues, there is usually very little pressure on these caps.
I say usually because there is always an exception but its not the norm.
The higher the pressure on the lobe the more critical proper break in becomes.
High spring pressure rates can be caused for the most part by..

High pressure springs.
Multiple valves being operated by the same lobe.
High ratio rocker arms or followers.

Some budget tuners sometimes elect to go with a higher ration rocker arm instead of a higher lift cam, while it does effectively provide lift it doesn't change the duration and puts a lot more strain on the cam lobes.
Zinc content was always a way of protecting the cam but levels are much lower today, a zinc additive may be of some benefit in these engines or an oil formulated to old specs like SL or even SG.

 

[Trav]

I forgot to mention, this is mostly applicable to older engines of specific designs or flat tappets.
Most cams the operate the valve directly or cams that use roller lifters don't suffer these issues.
Higher ratio rockers could possibly be a strain of the OEM roller lifter bearings and push rods though i have not seen it i have heard it reported.

 

[Gene K]

Originally Posted By: Trav
I forgot to mention, this is mostly applicable to older engines of specific designs or flat tappets.
Most cams the operate the valve directly or cams that use roller lifters don't suffer these issues.
Higher ratio rockers could possibly be a strain of the OEM roller lifter bearings and push rods though i have not seen it i have heard it reported.


If you put enough pressure on the lobes even rollers will wear cams. You sometimes see it in diesels. A gasoline engine with 700 lb or so of valve spring pressure (some race engines) might have this issue as well.

 

[Trav]

Interesting Gene i didn't know that with the roller lifters in diesels but it makes sense, the diesels i worked on were MB and MAN diesels but that was over 20 years ago.

 

[Mackelroy]

Thanks Trav,

IMO, the 15w40 diesil oils are fairly safe in this regard, but yeah the zinc content has been on the decline with car and many mc oils. If I had to run 8,000 mile oil changes on my bike. It would be on oils like 20w50 Amsoil, 20w50 mobil vtwin oils. They still have a substantial zinc PPo and viscosity film strength.

One time, in the winter, I rode straight 30 weight castrol in my vfr for 400 miles, that stuff drained so thin it scared me, Ive never seen even a 1ow30 out of a car with 7 or 8 thousand miles drain that thin. Not even a Drip period at the end of the drain time, it was out in 30seconds , and no drip, now thats thin.