Zinc/Phosphorus Environment and Catalytic Q

[soundwavefd]

I am thinking of running Valvoline VR1 racing conventional motor oil in my 1993 Mazda RX-7 Twin Turbo (18,500 orginal miles). It is ZDDP reinforced. The levels of Zinc/Phosphorus are .14/.13.

I was wondering two things. How high are those levels really? Do they pose a real threat to either the environment or my catalytic converters? How fast will an oil with those zddp levels kill my cats?

My car's manual originally called for a "SG" oil and I heard "SG" oils back in the day had Zinc/Phos levels of .12/.13 based on something I read (On wiki so not sure if true). So am I correct in assuming that by using VR1 with Zinc/phos of .14/.13 I am really not using much more ZDDP than what would have already been in an "SG" oil back in 1993?

Thanks,
Drew

 

[PhillyJoe]

Your thinking is about right. Zinc/Phos have been consistantly reduced with each new designation; SL, SM, SN. Car manufacturers needed/were told to increase the life of the cat warranty. If your car doesn't burn oil, the z/ph will never get to the cat anyway.

 

[ARCOgraphite]

You can always run 4T superbike oil which is usually dual rated (obsolete?) API-SH

 

[Clevy]

Originally Posted By: ARCOgraphite
You can always run 4T superbike oil which is usually dual rated (obsolete?) API-SH

Every 4t oil I've seen was SJ rated. I'm not sure I've ever seen an SH rated oil.

 

[LeakySeals]

Way I see it...

Extending the life of the cat with API SN somehow morphed into killing the cat if you use anything else.

Newer vehicles (approx 04+) must adhere to tougher emission standards. This is achieved with cleaner running engines and higher catalyst efficiency standards. The higher catalyst efficiency standards are a combination of better catalyst media and ECU programming with higher efficiency thresholds (in some cases 90%). A higher catalyst efficiency threshold means a catalyst efficiency CEL sooner. Forcing replacement of the catalyst to pass inspection even though the catalyst is functioning at a high level.

As we know, some oil additives diminish catalyst efficiency when consumed over a period of time. This is where SN came in. Lowering the additives that diminish efficiency, extending the life of the cat. As stated above, on newer cars that life can be only 10% of its real life. Means your replacing cats that are 90% good just to put the light out.

Soo..if your 04+ use of SN recommended but not mandatory. If your pre 04 you don't have the high bar programming for catalyst efficiency and can use whatever you want.

 

[gomes512]

Seems on par with the SG rated oils all right.

I always wondered about the old school rotaries, I mean these burn oil by design right? What was the expected cat. life for those back in the day? Any mention of emissions equipment warranty in the manual? Was it the typical 5yrs 50K?

 

[getnpsi]

As a native California resident, I fully regret not learning spanish, and learning how to weld my own exhaust systems. Shelled out thousands for legal and illegal paths to satisfy registration.

 

[soundwavefd]

Originally Posted By: gomes512
Seems on par with the SG rated oils all right.

I always wondered about the old school rotaries, I mean these burn oil by design right? What was the expected cat. life for those back in the day? Any mention of emissions equipment warranty in the manual? Was it the typical 5yrs 50K?


When you say "seems on par" do you mean the zinc/phos levels of the VR1 will be close to the "SG" levels? I had read that about "SG" levels but was not sure if true. As far as emissions warranty I read that related parts is 24 mo or 24,000 miles, and specific parts is 60 mo or 50,000 miles.

 

[soundwavefd]

Rotaries do burn oil by design which is why I'm worried about the environmental and catalytic converter issues of running VR1. I have been recommended VR1 by highly respected RX-7 forum members but most of them dont run cats. I have all my original cats so I was just wondering how bad I would be mistreating them (and the environment) by using VR1. (VR1 Zinc/Phos .14/.13)

 

[Clevy]

Originally Posted By: LeakySeals
Way I see it...

Extending the life of the cat with API SN somehow morphed into killing the cat if you use anything else.

Newer vehicles (approx 04+) must adhere to tougher emission standards. This is achieved with cleaner running engines and higher catalyst efficiency standards. The higher catalyst efficiency standards are a combination of better catalyst media and ECU programming with higher efficiency thresholds (in some cases 90%). A higher catalyst efficiency threshold means a catalyst efficiency CEL sooner. Forcing replacement of the catalyst to pass inspection
even though the catalyst is functioning at a high level.

As we know, some oil additives diminish catalyst efficiency when consumed over a period of time. This is where SN came in. Lowering the additives that diminish efficiency, extending the life of the cat. As stated above, on newer cars that life can be only 10% of its real life. Means your replacing cats that are 90% good just to put the light out.

Soo..if your 04+ use of SN recommended but not mandatory. If your pre 04 you don't have the high bar programming for catalyst efficiency and can use whatever you want.

Great answer. Sounds logical to me. It makes sense that emissions standards weren't as strict when this particular car was built.
And they do burn oil by design. The oil creates the combustion chamber seal so some oil is consumed every time the spark plug fires.
Great discussion guys

 

[Garak]

Originally Posted By: soundwavefd
So am I correct in assuming that by using VR1 with Zinc/phos of .14/.13 I am really not using much more ZDDP than what would have already been in an "SG" oil back in 1993?


Maybe, maybe not. Some of the oils from the day definitely did not have that much ZDDP, some did. In any case, in the cab fleet with such oils (and earlier), we didn't see a lot of premature cat failures. Do the rotaries benefit from enhanced ZDDP?

 

[soundwavefd]

I have heard from a very respected member on my forum that rotaries would benefit from ZDDP. I just had those two concerns about using them (Cats and Environment) but I dont know how big of an issue my concerns are.

 

[Garak]

Fair enough. I don't know how picky your jurisdiction is on emissions equipment, but that's something to think about. As others have mentioned in various threads on rotaries here, some people have eliminated the oil injection system and simply used an appropriate two stroke oil in the fuel. That would be another option, if one were so inclined to do so. I have no idea how big of a job that would be, though.

If it were me, I'd use the VR-1 10w-30 or something similar and be done with it. It sounds like a sensible option. I wouldn't be terribly concerned that it would cut the life of your cats; they've been on there likely a very long time anyhow.

 

[soundwavefd]

I know it is close to impossible to really know the answer but can anyone tell me how quickly VR1 levels of zinc/phos will kill my cats if my engine does indeed burn a good bit of oil? Even a ballpark figure would help. I just dont know if we are talking 10,000 miles or 100,000 miles.

 

[Garak]

You're "probably" going to be looking at a reasonably lengthy cat life. Of course, this depends upon how long they've been on there already. In the taxis with SF and SG oils, even oil burners wouldn't plug the cats for at least a couple hundred thousand miles. These vehicles ranged from around the 1979 to 1986 model years, so obviously some didn't have cats. With slightly later stuff, it was harder to tell because we had a few cars get totaled off, which skewed the data.