California smog and high ZPPD oil

[j_beede]

I did a search for ZPPD and SMOG and expected to see a bunch of hits--nope.

 

I was planning on replacing the Syntec 5W-40 in my MY05 C2 with J Gibbs DT40 5W-40 this weekend. I am being told that high ZPPD oil (like DT40 which is "unapproved") will result in catalytic converter failure. I am also being told that DT40 has only slightly more zinc than Mobil1.

 

Anyone have actual experience with CA smog and high ZPPD oil?

 

[JFP in PA]

I did a search for ZPPD and SMOG and expected to see a bunch of hits--nope.

 

I was planning on replacing the Syntec 5W-40 in my MY05 C2 with J Gibbs DT40 5W-40 this weekend. I am being told that high ZPPD oil (like DT40 which is "unapproved") will result in catalytic converter failure. I am also being told that DT40 has only slightly more zinc than Mobil1.

 

Anyone have actual experience with CA smog and high ZPPD oil?

 

First of all, yes, ZDDP will shorten the life of the cats, but the larger argument is by how much.  Because the EPA has the OEM's on the hook to replace the converters under warranty for up to 8 years or 80K miles, they lobbied the EPA to force lowering the ZDDP levels in an attempt to help them get off that hook.  Unfortunately, ZDDP is the best anti wear additive available for engine oils, which means that low ZDDP oils allow engine wear that ZDDP would have prevented.  Best part of this argument is that without very sophisticated laboratory analysis, it is not possible to tell if ZDDP or crap gas additives were the cause of cat failure.

 

While nearly no one reveals that actual ZDDP levels in oils these days, UOA's have shown that DT40 after more than 7K miles still has more ZDDP remaining than M1 has fresh out of the bottle.

 

Perhaps a better way to look at the argument is that you as the car's owner need to make a choice between replacing the cats, which only requires some hand tools, or potentially having to rebuild or replace your engine, which is both more expensive than the cats and requires a lot more tooling.  I know where I and my customer's fall on that call. 

 

You also need to note that if your cats do actually go bad, the car will code and tell you long before you go anywhere near CA Smog.

[j_beede]

Thanks for that detailed response.