just read this post man 56roger your a guy after my own heart.could not have said it better.my whole live has been thats not the way everyone else is doing it.get lost.

other things that may contribute to cam failure
oil with low breakdown#S
no presure in rocker shafts(90% of rockershafts i have dismant for re use had gauled rocker arms as well as worn shafts. reason is bleed off tubes. ) my take is no bleed off, block them . the oil leakage will work down to dist gear and time chain.
the gaulimg of rocker assembly must be hard on cam and lifters

I've read several tests on the break down, I don't recall if the Delo 400 that was tested was the new synthetic or the old conventional. I'm using the old conventional 15-40. I'm not concerned about the lower break down on a stock 223 six, If I had some wild cam and high valve spring pressures I would. I just used the last of the old conventional on my last oil change, so I'll be looking at using something different in the future..

5/30pennzoil ultra 115612psi before break down
rotela t    (10w30 valvoline nsl 105000 break down
71214 psi at breakdown new retell t 15w40 72022 at break down.
dello 400 5w40 69631 at breakdown
info from speed talk re test info diesel oil and gas engine oil tests

The Germans were probably doing it in WWII or before.

Given the following, I'd say that most diesel cams are nitrided, along with other components subject to high contact pressure.

http://papers.sae.org/2004-01-1448/

About 12 years ago I got 20 one gallon bottles of Delo400 15-40 from a neighbor and I have been running it in my 223 six in my F100 truck ever since, engine had about 40,000 miles on it and now  has about 70,000 miles using it. So my question is, if it causes problems with the cam what is the difference in a diesel cam? Old diesels would run 200-300,000 miles with no problems..

56 rodger,and ted, you should both read the test results from stately labs of sparks nevada(now called ALS teck.Ted is close in his remarks but some difference in the test results. 56 roger is from another world which is fine.  the info i s[peak of was noted as 
diesel oil 'lab tests" and Wear test Results. speed talk. a very good read .if ether of you want i could mail you copy of some 30 pages of results.just send me your mail address to ct1940@shaw.ca..
my first job was in a loging camp,they used only series1 engine oil for gas and diesel engines. my car was a 1955meteor 272. I had axcess to free oil changes used this oil for years,sold the car with 100,000 miles. never had to even set the valves,checked them and under the valve covers like new.this ws in 1957and series 1 oil was a detergent oil for diesel engines.But modern diesel lube oils are entirely a different animal and not to be used on gas engines, especially flat tappet cams.
 hear we go again on oil discussions,but what better to do with our time(some times in the past


2shaw.ca

I have been using the original Rotella 'T' for 10 years (more zinc than 'T-3'), and changing it often.  I have to wonder if alternating between high detergent Rotella and a high-zinc/low-detergent racing type oil might not be a good idea?  The racing oil would lay down a fresh zinc layer to protect the cam/cylinder walls, and the Rotella would keep it from building up with the resulting layering grief that Ted describes (?).

6 VOLTS/POS. GRD. NW INDIANA

The flanks are those areas of the lobe before and after the nose where the valve is either opening or closing.  While the lobe area taking the highest load hit is the nose of the camshaft, the flanks are still taking a beating and especially where the lash is just taken up and the valve starts to lift off of its seat.  Pitting is just one of the effects seen on those flanks where ‘zinc overloading’ or the opposite where the oil itself is not providing adequate pressure lubrication.
 
Over the course of time, I’ve found three topics that will always bring on a spirited discussion; religion, politics, and engine oil.  Here are my thoughts on engine oil in general.
 
While oil with reduced amounts of zinc/phosphorus (ZDDP) can be compensated for by simply changing the oil more frequently, too much ZDDP creates a situation where the zinc can build up in an excessive layer on the lobe/tappets and in turn can force premature wear in that area when those layers are peeled away when those layers get to high for the metal parts to simply slide over them.
 
Diesel engine oil is higher in detergent than gasoline engine oil and part of that is to combat the excess diesel fuel that gets past the rings on a diesel engine.  If the detergent level is too high, then the detergent can strip the zinc away from the metal parts to which they have adhered and especially if the zinc levels are on the high side where it is layering on the metal to metal contact parts.  Even the reduced amount of detergent in an API service rated oil for a production gasoline car engine is likewise too much in a race engine.   That detergent ends up being detrimental in that the detergent can work its way up past the rings and into the combustion chamber thus making for some unwanted detonation.  Many of the race oils are very low in detergent if they have any at all for this reason and subsequently must be changed out more often. 
 
I was part of a two year episode of engine teardowns performed back in the Seventies where diesel oil versus gasoline oil was used in gasoline engines only.  The diesel rated oil resulted in a measurable increase in both cylinder wall wear and bearing wear when looking at engines with 100K miles on them.  Part of that has to do with the brand of oil while another factor is diesel oil having a lower percentage of base stock oil.  Engine oil technology for the flat tappet engines was at its peak in the late Seventies/early Eighties and with the advent of roller tappet camshafts across the board, the oils have become more application specific.
 
As always, this is just food for thought.  Having worked on engines for almost fifty years now, I’ve torn down a multitude of engines run on the various engine oils which has defined what oils I run in my own engines as well as the engines I build for customers.

Lorena, Texas (South of Waco)