Why ZDDP is fine in today's engines

[Pete591]

Unless your car engine burns oil...ZDDP will never have any significant effect on your catalytic converter. Ever. Period.

ZDDP works...most lower viscosities of oil are low in ZDDP. This is one case where an additive makes sense or use an SL oil like Royal Purple.

Me like ZDDP...it works...my usual senseless .o2

 

[JHZR2]

ZDDP is in some ways an "obsolete" additive, which only has superior efficacy in some specific designs for engines. Why folks make such a deal over ZDDP is beyond me, it is kind of like making a big deal over group III vs IV.

Long story short:
-ZDDP is known to harm catalytic converters, but it takes a lot to do so.
-If your engine doesnt burn oil, high ZDDP will likely not make any difference
-ZDDP is decades old technology, with modern criticality only to flat tappet cam engines. Anything else will do as well if not better with modern chemistries, which are balanced with ZDDP and other adds.

I have to laugh when folks gripe about the "value proposition" of having group III vs IV, but then want tons of cheap, old-tech adds.

 

[Michael_P]

Some modern Euro and Japanese engines have the cam riding straight on the lifters with no roller rockers. These engines can benefit from ZDDP in the 1000ppm range, though not necessary due to light valve springs. I run SM in my 01 Protoge' with no worries. Save the high ZDDP for the cammed up thumpers.

 

[JHZR2]

But if you read the API specs, the ZDDP level can var by viscosity getting you into that optimal range if necessary. It is all about the selection of oil, and the ZDDP can be had if there is a reason of concern by changing oil grade.

 

[m37charlie]

When Mobil was developing the CH4 version of Delvac 1 5W40, they increased P from 1160ppm to 1350ppm "primarily to improve wear protection at high level of used oil soot", even for modern lower rpm heavy truck diesels. Zn went from 1300 to 1490.
SAE Technical Article 2000-01-1993 "Performance of an Advanced Synthetic Diesel Engine Oil", p.8
They were designing the oil for OCIs of up to 100,000 miles, with top-ups of course.
Incidentally all cars and trucks burn oil. The only question is how much. For very long OCIs a moderate level of oil burning (0.1-0.2% fuel rate) is a blessing, it allows top-ups with fresh oil.

Charlie

 

[JHZR2]

articles from 2000 are obsolete too. what level of zddp does D1 have today? Does it work fine?

 

[m37charlie]

It depends which Delvac 1 you are talking about.
D1 ESP ~11-1200ppm P (CJ4)
D1 plain ?? (CI4+)
D1 LE ~800ppm P (E6/E4)
D1 SHC 1100 ppm P (E5/E4)
At least I found a literature reference addressing the subject.

Charlie

 

[JHZR2]

I hear you... But citing other SAE papers (newer ones no less) on the effect of syn vs conventional on fuel economy and wear rates were determined to be irrelevant due to the multiple formulation changes since the paper dates (which IIRC was 2004).

Given that ZDDP is a major player in the wear considerations - Id say that the aspects of wear considerations and changes in chemistry to prevent wear may have obsoleted it...

my 2c.