[TR] oil science and break-in question

[Tony Drews]

I'd tend to continue to use oils with a higher ZDDP level than the 
run of the mill oil.  There are some varieties that aren't terribly 
expensive.  Valvoline makes a few (like the VR-1 line), I think 
Castrol has seen the light on one or two of its oils too.

Part of the equation is how much force is being placed on the tappet 
- having heavy valve springs and a high lift cam certainly can 
increase the forces and make the engine more sensitive to this, but 
the forces placed on the tappet are kind of one of those black art 
things.  A low lift cam with improper ramps can cause all sorts of 
interesting / bad forces.

Just using high ZDDP for break-in doesn't protect the cam and tappets 
for life.  But the break-in period (especially the first 20 minutes 
after the rebuild) are very key to getting the cam and tappets happy 
with each other.

Tony Drews

At 06:19 PM 3/7/2013, Randall wrote:
>---- "Fisher wrote:
> > I have a question, and I will lob it out there for any and all to answer.
> > Once I have broken in my flat tappet cam with the proper break-in 
> oil, can my
> > film of lubricity then be washed away if I use modern oils after that?
>
>Assuming you mean the microscopic film from ZDDP, then I believe the 
>answer is yes.  As I understand it, when the film of regular oil 
>breaks down and allows metal-to-metal contact, the film left by the 
>ZDDP acts as a dry lubricant but eventually gets rubbed away and 
>then grows back if there is enough ZDDP in the oil so it can be 
>rubbed away next time.
>
>Whether that ever happens in a stock TR motor is a different 
>question.  I remain unconvinced, especially since I covered several 
>hundred thousand miles with "low zinc" oil in a TR3 
>motor.  Unfortunately, that engine already had significant cam wear 
>when it came to me (as shown by measured lift being low), so tearing 
>it down wouldn't prove much of anything.
>
>- Randall
>
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