diesel oil in older engines- RE: cats etc

[928]

Question for the smart guys-The printed matter that I could find all suggest that you not use diesel oil in a car with emission equip, due to the high zddp & phosperous fouling the cats & sensor.

I'm having trouble understanding - the car is an 86 porsche 928 with a cat & o2 sensor. Not able to find any info on zddp levels etc of oils from '86 until they reduced the levels. It was probably 20+ years of using the previous levels of zddp & phos. & the cats still work. I can understand not using diesel oil in a modern car , but if it was ok (& the only thing you could get) to use high zddp & phos what has changed?
Oil in question is Valvoline Premium Blue 15/40- per valvoline:

thank you for contacting Valvoline Product Support. Our current CK-4 formulation of Premium Blue 8600 ES 15W-40 motor oil contains 1,210 ppm zinc and 1,100 ppm phosphorus.

 

[hatt]

Lawyers and accountants write the spec requirements and literature. That's why you don't understand it. ObviouslY HDEO will be fine.

 

[Garak]

Oils contemporary to the car in question would have been able to have phosphorus levels at the level in any event. Some will have had less, some will have had more.

What's really changed is that OEMs are required to warranty emissions components for a longer period of time, and reduced phosphorus oils can help them reduce warranty costs. Many here have used HDEOs in gasoline cars with great success. Doug Hillary, who posts here from time to time, used Delvac 1 5w-40 in CI-4/CI-4+/SL, I believe it was, in his Porsche examples over the past number of years.

Note that even an A3/B4 type Porsche approved lube will have elevated phosphorus.

 

[Garak]

Originally Posted By: hatt
Lawyers and accountants write the spec requirements and literature.

Don't forget the marketing people.

 

[Ducked]

Does it affect the O2 sensor? Thought it was just the cat.

 

[Kamele0N]

According to the internet API SG had around 1200ppm P/Zn...

 

[Snagglefoot]

Your 86 cat might be non functional anyway.

 

[JHZR2]

Originally Posted By: 928
I can understand not using diesel oil in a modern car , but if it was ok (& the only thing you could get) to use high zddp & phos what has changed?
Oil in question is Valvoline Premium Blue 15/40- per valvoline:

thank you for contacting Valvoline Product Support. Our current CK-4 formulation of Premium Blue 8600 ES 15W-40 motor oil contains 1,210 ppm zinc and 1,100 ppm phosphorus.



What has changed is that oil additives other than ZDDP have gotten better, and basestocks and additives have necessarily had to change do support higher power density and higher performing engines.

With emission control going into diesels, additives that had the potential to poison those in diesels come into play. But we're not talking about diesels or modern trucks.

What were really talking about is longevity of emissions equipment in old vehicles. Vehicles that may not have even come with post-cat sensors to track efficiency, longer warranties legally mandated, etc. When your vehicle was built, much of that wasnt in play. Now it is. So you cant compare modern specs to prior reasoning.

The real question is if the reduced ZDDP has any effect on longevity. Since its still reasonably high (vs 800 ppm for most PCMOs), it should be decent. Im actually surprised that the CK-4 formulation doesnt have lower ZDDP than what Valvoline has said.

 

[BrocLuno]

The higher levels mean something IF the engine is consuming oil. If the engine is using very little, it makes no difference as in it ain't going into the smog system anyway ...

Been running diesel engine oil in CAT equipped vehicles for over 30 years now, and they still pass SMOG to well beyond 200,000 miles. That is all sorts of vehicles - VW, Audi, Jag, Ford, Saab, BMW, etc.

OTOH, a one time head gasket failure and slug of antifreeze will kill a CAT in a heart beat