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MG Midget and Sprite Technical - ZDDPlus - what is it?

I have been given a bottle of ZDDPlus. This is an oil additive suplied by Frost (the well known car restoration and tool supliers). The bottle says "rstores ZDDP levels to SF levels". It also says "This product is intended foruse in pre-obd, off-road, industrial, agricultural and racing vehicles only". Can anyone explain what ZDDP is? For that matter, what is pre-OBD?

I'm generally skeptical of oil additives (if there was a benefit then surely the oil companies would have thought of using it). I am currently using Mobil 1 10/60 oil. Is there any benefit or harm from using this?
Chris H (1970 Midget 1275)

It's a substance that used to be present in oils but was removed (or quantities reduced) to meet pollution standards.

http://www.millersoils.net/1_Millers_r_AUTO_ZDDP.htm

OBD is On-board diagnostics, it became very widespread when pollution requirements became more stringent as it allows very fine control of the engine (anti-knock sensors, lambda sensors and the like.
OrangeSpyderMan

lack of ZDDP is not a problem in engine oil but is perceived to be in gearbox and diff oils for our sort of cars, so I'd use it in them.
David Smith

ZDDP is a sort of zinc -di -do- phosphor bla bla compound.

We really need this in our pushrod engines, it lubricates and protects the cam and followers, the forces between those are too high for oil.

It was slowly fased out because catalytic converters can't stand it.
Alex G Matla

I thought that the lack of ZDDP in modern oils was responsible for premature wear on camshafts and followers.
Dave O'Neill2

What Barney (and Crane Cams) says http://mgaguru.com/mgtech/engine/cm108.htm
Geoff Ev

my mistake, sorry.
David Smith

So - is the answer to my question, it is a good thing to add ZDDP (or at least it will not do any harm)?
Chris H (1970 Midget 1275)

It it was me (disclaimer etc) I wouldn't use it because I'd already be using an oil that I know has appropriate ZDDP levels. If for some reason the oil I was using did not have suitable levels, I'd change the oil I was using...

If it was Nigel, he'd say to consult the owner's handbook (NOT Haynes), if it was Lawrence, he'd say the opposite of what Nigel says, and if it was Prop he'd add a ZDDP gauge and top up the ZDDP levels as they fell.

:)

I think it's a kinda make your own mind up - the consensus on the posts here is that you need ZDDP, so either use an oil with enough in, or use the additive if you can't/don't want to use such an oil.

OrangeSpyderMan

Ahh ZDDP, Tribology was my specialism at university!

So here it goes: laymens terms. ZDDP mainly acts as an antiwear additive, it also has corrosion prohibitors in it. They are the two main functions of it.

It is a very common additive and will be present at some level in all modern oils. Whether or not it was present in the oil which left the factory is a 50 50 guess - but I doubt it.

The reccomended. Castrol classic oil is likely not to have it, in fact I don't think it has any modifiers. - but check this.

However, i'm sure it won't harm anything. At the moment I have the castrol in my 1500 triumph... but any old oil will do that engine... i've had a cheap sythetic in before now.

You need to consider its affect on things like fibre washers and seals... these are the only things it can really harm. I don't know what its effect is on these, or whether your engine/gearbox/clutch??? is built... Does the 1275 have a wet clutch? surely not?

Christian
C L Carter

I think the point is there used to be lots of it in old oils, and much less now.

Old engines work best with the amounts that were used when they were designed, and new engines work well with the amounts that are used now.

A lot of well-respected classic oils contain more ZDDP accordingly, as per the links in the previous posts.

I would avoid cheap modern synthetics because - ZDDP content tends to be lower and detergent content tends to be much higher.

Then again, as I said, it's a you pays your money, you makes your choice thing.

OrangeSpyderMan

OSM the point is, ZDDP is a useful additive and has been used in oils for many years but has been much reduced or even eliminated recently as it wrecks catalytic converters. So the choices you mention are not really open to us. However my view is it's a bit like unleaded and valve setas, the hype is far larger than the actual effects.
David Smith

David, Miller's claim (I have no means of checking, admittedly) that their classic oils contain "old school" levels of ZDDP (my first post in the thread has the claim), but I'm sure there are others.

That's what I use, though it might be hype. I have an unleaded head too :/
OrangeSpyderMan

OSM,
you're (partly) wrong about me

yes I'd say as a start consult the Handbook and stick with it and the Haynes has mistakes in it :)

but as you become more experienced with your car then you can start to deviate

I used to put a good quality fully synthetic engine oil in my classics nearly 20 years ago against the concenus of advice given then (a rebel like Lawrence then) and I used to do tens (and tens) of thousands of miles in them with no issues

like you say a lot of these things are more a matter of belief than logic so do what keeps you happy
Nigel Atkins

For once I'm only partly wrong, I'll chalk that up as a win :)

No offence meant at all, I was just teasing, sorry if any was taken.
OrangeSpyderMan

Well, there's a myriad of threads in the archive about this.

Easy solution: put in classic oil, like Castrol or Millers, with enough and the correct additives.

Or, maybe there are two volunteers rebuilding an engine now and are willing to experiment; one uses full synthetic from scratch and the other Millers. After 10 or 20.000 mls take the engines apart again.
The only way to be sure. 8^)
Alex G Matla

OSM,
no worries I didn't even take a gate :)
Nigel Atkins

This thread was discussed between 11/01/2012 and 12/01/2012

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