Does the 6.0 V12 need ZDDP?

 

I never heard of ZDDP.
What is that?

 

The problem with ZDDP is the cataverter. Rumor has it that ZINC damages the verter.

I use it in my wife's VW 2004 NB TDI with 406,000 miles on the engine but I don't live in an EPA 'non-attainment' county in Texas. Diesels are not tested in Texas for emissions anyway.

The VW PD TDI engines have a reputation of unusual camshaft wear so I use it as a precaution.

If the cataverter damage does NOT bother you, then use it for flat tappet engines.

 

Convertors? We don't need any stinkin convertors.

Seriously, isn't the V12 a flat tappet engine? And as such, shouldn't ZDDP be used?

 

ZDDP is in "High Mileage" car oils in greater amounts. It helps with non-roller bearing design valve trains such as the Jag engines.

I saw an independent study one time on the effect of additives with ZDDP added to various engine oils. The results basically said that sometimes the additive made things worse. The conclusion was that additives in modern oils are a balance and that adding more ZDDP to an oil could upset that balance. They recommended using an oil that was manufactured with more ZDDP in it because the additives were balanced.
Attached is a chart from Mobile on Zinc and phosphorus levels (ZDDP). Note that 15W-50, which is good for the V12, is very high in both.

 

Hi gents.

Bringing this back up because I am wondering if the AJ6 / AJ16 engines need Zddp. The formulation I was going with has now dropped to 900 from 1000. I do know that they are DOHC but are still flat tappet.

any thoughts ?

 

If you car has roller tappets, you are OK using an oil with reduced levels of ZDDP.

If your car has flat tappets, you need the protection that ZDDP offers. You can either buy a ZDDP additive or use an oil with the higher levels of ZDDP. I personally use either a diesel rated oil (Rotella T5 is my current favorite), Valvoline VR-1 High Zinc (I can only find it in 20w-50), or Brad Penn motor oil (expensive but good).

Here's what happens to a flat tappet if you use the wrong oil. I pulled this from an MGB I was restoring. The lifter had spalled and the camshaft was chewed up. Not sure which happened first and I am not sure it really matters.


There are some who say that you only need the elevated levels of ZDDP during break in. My personal opinion is it's most important during break in but still needed during operation.

The levels of zinc and phosphorus were reduced sometime in the 90's to keep blow-by from poisoning the cats. It wasn't the last time the longevity of the engine was sacrificed for emissions control. If you're bored read about how the newest Mercedes diesel engine sacrifices itself to keep the diesel filter from dying.

 

Thanks for your response. Yes, the AJ6/16 is a flat tappet, but it’s a DOHC so the argument is that it does not benefit from the ZDDP. Now, the ZDDP , in most Mobil products has gone below 1000, and possibly in others too. So we can say that any oil will do all day long, but if ZDDP is needed, we will find out soon what a sub 1000 content will do sooner rather than later.

 

Sounds like a conversation to bring up at the bitog websites....the hole is deep, rabbit.

 

I did. No resolution. Some folks think that it does others that it doesn’t. Since It’s not a “grade” or a “brand” discussion,but rather a discussion about an ingredient that is being eliminated across the board, I don’t think many people are really equipped to give an answer. Either a DOHC “flat tapped” engine needs at least 1000 ppm zddp or it doesn’t . And I have no clue what the answer is. All I know is that the latest reformulation of the oil I use dropped it under 1000, and so have many others.

 

In my mind, the question is less about SOHC, DOHC, or QOHC - it's flat tappets or roller lifters. If your car has roller lifters you can get by with the lower zinc/phosphorus levels because of the nifty roller wheel. If you have flat tappets, regardless of how many cams you have, the higher zinc/phosphorus levels provide the protection needed for the cam and lifter.

On the other hand, it's not like it's something that happens right away. My dad has a B-body Mopar with the 383/4-barrel engine. He has ignored my advice for the last ~15 years about being careful about what oil he puts in it, and is just now starting to see the effects of the cams/lifters eating each other up. I think he has another year, maybe 2 at the most before we have to pull the engine and rebuild it.

I'm not trying to start a holy war and I'm not trying to sell anyone to my way of thinking. I have personally seen the effects of the ZDDP change in my own cars and learned my lessons the hard and expensive way. At the end of the day it's your car and your decision to make.

 

I use that Rotella T5 as well. Stopped tapping in my 86 928 in a beautiful way. From there it became my thing - smoother running in the XK8 and XJS. I believe it quieted the XJS but I was too early on in the car to really know it well enough. Plus, it comes in an oversized jug (2.5 gallons I think) and is cheaper than other options. I personally think it a good thing. Me,,, although I like the zinc difference and the cost, I don't get all nutty about engine oil. For me this one just makes sense.

 

I am leaning in this direction too. I looked into it years ago and “felt” comfortable at 1000 zddp. My particular oil choice, had 1100 at the time. Now they’ve “reformulated” in 2019, but still sell the product under exactly the same name and label. Which is infuriating. Fortunately I look at data tables from time to time.

Problem with the Zddp discussion is that people start talking about their favorite brands and grades, which is irrelevant. I mean, it’s relevant, but indirectly. Jaguar allows for nearly every grade on the manual. The point is if either the V12 or the AJ6 or AJ16 need ZINC. People blow you of because they think it’s another “oil” conversation, and it’s not…... It’s about what the new and ever-plunging ZDDP levels in oils are going to do to these engines. We don’t know because we are just now getting to the point on below 800 in many brands that used to have above 1000 just 2 or 3 years ago. API SG and SH, which is what these engines where built for, had up to 1400.

So it boils down to this:

do you trust that whatever additive is being added to replace the removed zinc is good for the engine or not?

It could very well be. It could be whatever they are adding is infinitely superior to the Zinc…It could be that 1400 ppm or 800 ppm or 400ppm make ZERO difference in these engines. BUT WE DONT KNOW because these bigger companies aren’t testing their common shelf oils for the benefits or engines designed in the 70’s and 80’s like ours. (The AJ16 is a refined AJ6, but a AJ6 nevertheless)……They are not formulating standard shelf oil with the maintenance of older cars in mind. When they think of older vehicles they are thinking of a 2010 Toyota with 250k miles and still going. . Which is why several companies are starting to introduce “classic” lines.

I haven’t made up my mind, but I am seriously considering switching to something that has at least over 1000. It just has to check all my other personal boxes of grade and brand which are irrelevant to specifically the zinc issue.

 

FWIW, for the V12, Mobile 15W-50, according to the Mobil 1 spec sheet, has ZDDP over 1000 ppm. Their High Mileage oils have levels in the 800-900 range. They specify the zinc and phosphorus components of ZDDP separately in their literature. Their racing oils have even higher levels, but are harder to find and are generally not recommended for street use.

 

It's been 20+ years since the last AJ16 rolled off the line, much longer for the AJ6.

I don't believe most owners spent two seconds thinking about zinc. I don't think the oil change and auto shops have put much thought into it either. I'd say 95% of the AJ6/16 engines on the road today have been using oils with zinc levels <1,000ppm, and I don't believe there have been any widespread issues....quite frankly, these engines continue to enjoy 'bulletproof' status. I think if there was something to this zinc issue for these engines, we would have heard about it long ago.

That's my opinion, and I have very little fact to back that up.

I have used Castrol Edge oils for a long time. Apparently they don't say what their zinc levels are, but I believe I recall it's been claimed to be at <800ppm for a long time. I have read that, "API SM specifies that certified oil must have 800 ppm (parts per million) of ZDDP or less".

I drive my car every day. Have put on 70,000 miles on the car I drove to work in today. Could something reveal itself in another few years, I guess so, but there are people who have driven their cars for a lot longer than I have, bragging about the Walmart oils they have used over those hundreds of miles....without any hint of engine trouble or failure.

 

I just don’t think people who drive these cars have been using the lower grades in general. Even in the AJ16 cars. They use the heavier weights, which have, until now, had higher ZDDP. You use 0w40 if I recall and I use 10w40. Mine went from 1100 to 900. I know there have been reductions across the board with the latest reformulations. Mobil one told me on email and the phone that 1000 ppm is what they shoot for in older engines. Now, do they know the particulars of a V12 or AJ6/16 engine? Doubtful. And there will be further reductions. This was their written response to using their high mileage 10w40 which until a couple of years ago had 1100 ppm of zinc:

 

Hi gents,

For anyone interested, for my AJ16, XJS I did decide I agree with @Thorsen about the flat tappets in these cars…..and also with Mobil 1 and Amsoil and Redline (whom I also contacted) who all do recommend a oil with a ZDDP of at least 1000 for the flat tappet cars, Even DOHC. It might be something their computers spit out, and these engines might be perfectly fine with a considerably lower ZDDP than what they have seen before, but I don’t think I want to test that theory in my car. Specially as levels will continue to go further and further down in the mass oil producers try to meet the new API’s …..As I mentioned before, the latest reformulation of the oil I was using (Mobil 1 High Mileage 10 w 40) no longer meets those standards as it dipped below 1000 zddp as of 2019

I narrowed it down to a couple of options, Amsoil Z Rod 10w40 or Redline 10w40 and decided to go with the Redline. I wanted to stay on the same grade I was before and I wanted to stay with a full synthetic. Redline took the time on both email and over the phone to discuss my concerns about their seal conditioner package being as robust as the one in the Mobil 1 High Mileage I have been using. The Redline is definitely overkill for a boulevardier that gets driven once a week *if*it’s sunny out, but it checks my 1200 zddp and all other boxes.

 

You're favorite oil can be sweetened, if needed, with a ZDDP additive


Very easy solution !

Cheers
DD

 

Thanks !

…I prefer an oil that comes with the ZDDP in their package formulation . I don’t think I want to add an additive that may or may not have a reaction with the formula in the oil. ZDDP itself can be formulated differently from manufacturer to manufacturer, and I would just be cooking a witches brew using my engine as the pot.

 

That is the exact product I keep on the shelf for a 'few splashes' when I change the oil.