An Intelligent (I hope) question about ZDDP

[Jetronic]

Originally Posted By: Ducked
Originally Posted By: SR5
Originally Posted By: Solarent

The reason for this is easy to answer with simple math 800ppm x 0.79 (which is how much must be left after the IIIG) = 632ppm which is over the 600ppm minimum threshold.

Nice !!! Well explained, I never got that before. Thank you



Still don't get why its 0.79, a really weird number to pick for a standard.

It can't have been too much of a stretch to get to 80%, surely?


It isn't. look at it from the other side, you allow 20% loss of phosporous. that likely includes 20.9% aswell, and 21% is a fail. Turn it around again and anything over 79% passes.

 

[Bamaro]

Sorry if this was already discussed but I seem to remember an older thread saying that too much ZDDP can be a bad thing. Something about being corrosive if I remember correctly. True or false?

 

[SonofJoe]

I've only heard about ZDDP being corrosive since I joined BITOG. In the all the times I was playing around with them, I deffo wouldn't have said they were corrosive (except to silver bearings but this is a problem specific to railroad oils).

Under normal oil temperatures, I could well imagine ZDDP breaking down back to thioacid and zinc oxide but either the thioacid would react with metal parts (which it's supposed to) or with one of the many basic additives in oil (detergent, ashless, diphenylamine AO). If you went above 200C, then you might get some very corrosive mercaptides forming but (a) that would occur at all concentrations of ZDDP, both high & low and (b) if your oil's going above 200C you have more urgent problems to deal with than corrosion!

I do wonder if some of these stories about ZDDP being corrosive at high concentrations date from the '50s when ZDDP was the only additive in oil and oils were less 'self-neutralising' than they are today?

 

[SR5]

Originally Posted By: Bamaro
Sorry if this was already discussed but I seem to remember an older thread saying that too much ZDDP can be a bad thing. Something about being corrosive if I remember correctly. True or false?

I too have heard the rumors about ZDDP and corrosion, but only on BITOG, and I've never seen it backed up with a link to a paper or anything.

What I can say is that most SN & GF-5 oils have about 800 ppm Zinc, while in Australia Penrite have been making everyday oils with 1600 ppm zinc for decades. Penrite is a heavily used and well respected oil company here in Australia. I have been using their HPR 30 since the 80's (HPR 30 link). It was the second oil I ever purchased (after GTX 20W50) and I used nothing but 1600 ppm Zn HPR 30 for many years. As did many others, it was the performance oil to use back in the day, and it still sells well even now.

So if decades of double ILSAC levels of ZDDP causes no issue here, I would not be concerned. Maybe as Joe said, some very old formulations, or maybe some silly high concentrations. But I would not be concerned with any off the shelf oil you could buy today.

I'll also add that many mixed fleet HDEO's and modern name brand Motor Cycle oils contain high levels (> 1000 ppm) of zinc without issue.

 

[SR5]

From the MC UOA section:

This Valvoline VR-1 has 1360 ppm Zn
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4246972/

Rotella T6 5W40 has 1540 ppm Zn
https://bobistheoilguy.com/forums/ubbthreads.php/topics/3737201/

Red Line 20W50 has 1970 ppm Zn
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4199646/1/

 

[Garak]

Originally Posted By: SR5
I too have heard the rumors about ZDDP and corrosion, but only on BITOG, and I've never seen it backed up with a link to a paper or anything.

I suspect it won't be easy to find, either. I've never come across any primary sources. If Joe hasn't seen papers, maybe Mola or Ed Hackett have. The only actual written sources I've seen are in car magazines over the years, things like Popular Mechanics. I don't know if there's anything in any of the literature from the oil companies with respect to their exceedingly high ZDDP race oils.

Finding too-high phosphorus levels isn't easy, anyhow. The levels that would get me worried are probably over 1500 ppm, give or take, and that's not easy to find. One could do it with some dedicated race oils, but those aren't exactly advisable for normal, long term street use, either, they're expensive, and difficult to find, so the odds of me getting some "by accident" are slim to none.

At 1200 ppm or so, I wouldn't even worry about my cats, unless the thing was burning oil like crazy anyhow. If I was that worried, I wouldn't be using an HDEO.