Returning Member

Hi Mark,

Do you have a flat tappet or roller cam?

If it’s flat tappet, oil selection is critical in order to prevent premature cam failure; ask me how I know. 😉

Paul

@paul-blore

Hi Paul, roller cam and you may well have a point 🙁

Hi Mark,

If it's a roller cam there are no oil concerns.  Rollers don't need higher levels of zddp.

Flat tappets don’t NEED ZDDP, but they do need an oil that can withstand extreme pressures. ZDDP/zinc is just one of a number of possible additives used to withstand the pressures of flat tappet cams.

However, roller cams (as opposed to roller rockers) don’t need anything special in that regard and a good quality fully (esther) synthetic will be fine.

Paul

Posted by: @paul-blore

However, roller cams (as opposed to roller rockers) don’t need anything special in that regard and a good quality fully (esther) synthetic will be fine.

Paul

...which is exactly what I run in my flat-tappet 289, for the reasons Paul has stated.  Machining work was done to modern tolerances - bottom-end bearings were selectively chosen to give 0.0005-0.001" clearances.

Mind you, much as I like my engine oil, I've never gone as far as giving it a name.  I do use an ester synthetic, though...

Aargh. Bloody auto-correct on my iPhone. Give me back my Windows phone. 😁👍🏻

For flat tappet cams, 1/3 of a bottle of Comp Cams break in additive should be put in at each oil change. This helps the lifters revolve in their bores. No matter what oil you use, I would seriously consider this extra “insurance”

Simon

I've never added any additives, just used a very careful break-in procedure.  It's worth remembering that you can have too much ZDDP in engine oil (assuming that's the additive you're using...)

https://aaoil.co.uk/123579-2/

Interesting report but completely worthless without some sort of reference numbers on the graph. It could be 0-100% of the oil, in which case anything up to (say) 60% ZDDP is fine or it could be 0-1%, in which case only a tiny amount is ok......

simon

Hi Simon,

ZDDP has a corrosive effect on bearing metals, which seems counter-intuitive, given that we're using it to protect our engines. Too high concentrations have a detrimental effect and I'll try to find out what levels are "too much".

Having more ZDDP doesn't improve the cam protection, but it will run out sooner. The ZDDP is a sacrificial additive and gets used up with use.

I use Amsoil Signature Series 5W50, which, as far as I know, doesn't have any ZDDP, but it does have extremely high resistance to extreme pressures, which is what the ZDDP is there for.

Paul

Interesting, my info comes from Real Steel who built my engine. They told me that most decent oils nowadays don’t have enough to keep the lifters rotating in their bores. Obviously this is not good with the flat tappet arrangement we have in our engines. He told me to add just a third of a bottle of the running in additive at each oil change. Given that most of us change the oil in our “toys” pretty frequently the small extra insurance may not be needed. 

Simon

Hi Simon,

That is nonsense I’m afraid.

The ONLY reason for a zinc additive is to provide increased wear protection at the high-pressure contact point between the cam and flat-tappet follower.

To suggests that modern oils aren’t slippery enough to allow the followers to rotate is bollocks.

I said I would come back on how much zinc/ZDDP is too much. 1,400ppm will start to promote increased wear and anything more than 2,000ppm will actually start to attack iron at a molecular level.

Paul

When you have some time to spare, have a read of this:

https://540ratblog.wordpress.com  

Paul

Thanks for that Paul,

I'll be sure to pass on your comments to Mark next time I see him.

Simon