Shell Rotella T6 not good for catalytic converters

Mountainman · **Posted:** Mon Jan 14, 2019 2:08 pm

Something I've never seen mentioned before. Shell does not recommend T6 for autos with catalytic converters. If you live where you have emission testing, you might want to switch to chevron delo 400 xsp to avoid an expensive cat replacement eventually.

geordi · **Posted:** Mon Jan 14, 2019 2:30 pm

You SURE they are talking catalytics and not DPF?

Cats have been in use without much of a change in design for a few decades now, and they don't care one way or the other about the ash level in the oil. Ash content is the one thing that the VW people seem to have focused on as a problem for the DPF-equipped diesels, because it causes them to fill up faster. That is a dirty little secret of the DPF - all those fuel-wasting regeneration cycles that "burn off the soot" aren't ACTUALLY sending anything more out the tailpipe. It is wasting fuel to pulverize the soot and convert it to ash particles which are STORED in pockets in the DPF grid... Until such time as too much is stored (after 150k miles or so) and then the DPF must be physically removed, cut open, and cleaned in a special process.

As with everything else, it seems the VW DPF is designed in such a size that it shouldn't need to be removed for cleaning at any point during the warranty - even the new extended warranty. I'd imagine that other DPF vehicles are much the same, as I've seen advertisements for DPF removal and cleaning for heavy trucks. Oh yeah - and of course that cleaning isn't cheap, to the tune of at least a couple thousand bucks... AND it massively lowers your fuel mileage b/c of all the "cleaner emissions" from burning 40% more fuel.

Mountainman · **Posted:** Mon Jan 14, 2019 2:45 pm

geordi wrote:

You SURE they are talking catalytics and not DPF?

Cats have been in use without much of a change in design for a few decades now, and they don't care one way or the other about the ash level in the oil. Ash content is the one thing that the VW people seem to have focused on as a problem for the DPF-equipped diesels, because it causes them to fill up faster. That is a dirty little secret of the DPF - all those fuel-wasting regeneration cycles that "burn off the soot" aren't ACTUALLY sending anything more out the tailpipe. It is wasting fuel to pulverize the soot and convert it to ash particles which are STORED in pockets in the DPF grid... Until such time as too much is stored (after 150k miles or so) and then the DPF must be physically removed, cut open, and cleaned in a special process.

As with everything else, it seems the VW DPF is designed in such a size that it shouldn't need to be removed for cleaning at any point during the warranty - even the new extended warranty. I'd imagine that other DPF vehicles are much the same, as I've seen advertisements for DPF removal and cleaning for heavy trucks. Oh yeah - and of course that cleaning isn't cheap, to the tune of at least a couple thousand bucks... AND it massively lowers your fuel mileage b/c of all the "cleaner emissions" from burning 40% more fuel.

Yup, I believe it was high phosphorus content that they said damaged the cats. I can imagine that it's a glacially slow process, but IF the xsp is a better product, and maybe even less expensive, then why chance it?

Disclosure: I don't own any Chevron shares, but I do own some Exxon :jester:

flash7210 · **Posted:** Mon Jan 14, 2019 2:58 pm

Key word is AUTOs.
As in gasoline engines.
And is true for all oils that have a higher zinc and phosphorous content (ZDDP).

ZDDP was a commonly used engine oil anti-wear additive.
Over the years it has slowly been reduced to allow catalytic converters to survive past the auto manufacturers warranty period.

Look through any of the hot rod forums for comments about ZDDP and flat tappet cams and how many amateur engine builders wiped their new camshaft during the break-in because they used an off the shelf oil that didn't have enough ZDDP in it.

Modern engines with roller lifters/cam-followers can handle a reduced ZDDP content.

BITOG has plenty to say about it too.

papaindigo · **Posted:** Mon Jan 14, 2019 3:23 pm

Not a "simple" issue and has been around as a subject of discussion since at least 2010. Apparently highish phosphorous can over a period of time "poison" a catalytic converter if the engine is burning oil. What period of time and what burning oil means does not appear to be clear. Apparently until recently this has not been an issue big enough to get Shell or EPA attention so I gather it has not been a problem and to the extent it might be a problem it's limited to gas engines. What apparently has happened recently is that Shell dropped the "S" (e.g. gas engine) rating on T-6. For what it's worth 4-40 T-6 is rated CK-4 and CK-4 provides protection against catalyst poisoning and particulate filter blocking per API. So bottom line is this might mean something for gas engines but not diesel.

Personally IMHO if a gas engine is really burning oil then catalytic converter problems are the least of your worries.

flash7210 · **Posted:** Mon Jan 14, 2019 3:37 pm

papaindigo wrote:

Apparently highish phosphorous can over a period of time "poison" a catalytic converter if the engine is burning oil.

The engine doesn't have to be burning oil.
Apparently what happens is, the phosphorus falls out of suspension within the oil, gets mixed in with the crankcase vapors, and gets pulled into the intake through the PCV valve. Then goes out through the exhaust.
At least that's what I remember reading somewhere. Take it for what its worth.

But if you've ever seen what gets pulled out of the PCV and into the intake, on some of these newer GDI engines, it seems somewhat believable.

Mountainman · **Posted:** Mon Jan 14, 2019 3:47 pm

Thanks for the info fellas, I guess it's probably not worth worrying about. But, IF the XSP is better, then maybe it's worth switching if you can get it at a good price. I'm going to see if my oil is darker than usual with the switch, maybe indication of a reduction of deposits

flash7210 · **Posted:** Mon Jan 14, 2019 4:04 pm

Mountainman wrote:

Thanks for the info fellas, I guess it's probably not worth worrying about. But, IF the XSP is better, then maybe it's worth switching if you can get it at a good price. I'm going to see if my oil is darker than usual with the switch, maybe indication of a reduction of deposits

On any diesel engine, the oil is gonna quickly turn black from all the combustion soot.
This is a good thing.
You want the oil to hold all those microscopic carbon particles in suspension and not be deposited on all the shiny smooth rotating parts of the engine. (i.e. the roller bearings on the rocker arms)

Pretty much all the CK rated oils are the same.
The only differences are oil weight (10w-30, 15w-40, 5w-40) and base stock (conventional, synthetic, synthetic blend).
There are plenty of other silly details that are continuously debated over, but... :roll:

Note: some of your big diesel trucks include centrifuge filtration to remove the carbon particles form the oil.

geordi · **Posted:** Mon Jan 14, 2019 4:11 pm

As many of these engines that we have pulled apart... I don't know about you Nick, but I can count on one hand the number of engines that had thick sludgy deposits on the top of the head from the oil. I choose that location for my investigation usually b/c of three reasons:
1: The oil is not under pressure when flowing around the top of the head, it has already been sprayed from the lifters.
2: The oil can spread out and move at its own pace to flow down into the valve galleries - so it can spread out to a thin layer, dropping anything in suspension b/c it has the time to move slowly
3: The oil also has the chance to settle there on top of the head as the engine is off, there are a lot of places like around the bolts where there isn't "flowing" oil, so again plenty of opportunity for things to fall out of suspension and build up if they are there.

Thankfully the number of heads that have been coated in goo is very low - less than 5 of the 80 that I've worked on now, and of those, the owners said they didn't know the history but it would seem at least a couple had been abused by lack of proper maintenance.

My takeaways: Use any quality diesel rated fully-synthetic oil and change it no more than 6000 miles unless you are doing analysis faithfully... And you should be fine.

You don't need ZDDP additives, this engine doesn't have flat tappets (and even on my 2003 VW which DID have them, it made 400k miles on Turbo Diesel Truck or T6 oil)... So I think the talk about ZDDP is so much internet noise. Having a quality oil and keeping it clean is key. Oil might not "go bad" but it definitely gets dirty, and when it can't hold any more crap, that is when bad things start to happen. When the additive package in the oil is used up, bad chems can start to build up. Water contamination can build up from condensation bringing in things that probably shouldn't be there... Etc.

If you read the manual, the severe service schedule has a list of criteria that denotes "severe" service. This list isn't an all-or-nothing set. If you can say yes to ANY of those criteria - stop and go, dusty conditions, high speed driving, towing, hot conditions, cold conditions... Then you should be on the severe service schedule. Yes, EVERYONE should be on that schedule. The non-severe-service is just another way for Mopar to make it seem like you can go longer than you should - and disclaim any liability for themselves from you doing that.

I change my oil at 5k intervals b/c I don't do analysis. If you are doing testing, then follow their suggestions b/c you have the data to back that up. Doing 12k or longer changes without analysis... Is just asking for problems.

I put a 2-micron bypass filter kit on my 2003 VW, and it did exactly nothing to stop the soot from turning the oil black instantly. I wouldn't waste the time with that again.

WWDiesel · **Posted:** Mon Jan 14, 2019 6:09 pm

There is a simple solution if it is a Jeep CRD. Remove the CAT like many have already done and it becomes a non-issue.
It will not trip any DTC's and the Jeep will run better without the backpressure which lowers EGT's.
If you have to pass a visual inspection, remove the CAT, bust up and remove all the guts out of it and reinstall.
:SOMBRERO:

Mountainman · **Posted:** Mon Jan 14, 2019 6:10 pm

Yeah, I agree that these engines are very clean inside. The only ones I've seen with sludge had coolant in the oil via a bad head gasket.
I am very interested in lower temp starts from the XSP if it actually turns out that way, although just a $300 battery has me starting down to 8 degrees (after one or 2 fails), and that's with 7v steels...
But, a lot of people have trouble with cold starts, and maybe they should try out the chevron product.

Mountainman · **Posted:** Mon Jan 14, 2019 6:13 pm

WWDiesel wrote:

There is a simple solution if it is a Jeep CRD. Remove the CAT like many have already done and it becomes a non-issue.
It will not trip any DTC's and the Jeep will run better without the backpressure which lowers EGT's.
If you have to pass a visual inspection, remove the CAT, bust up and remove all the guts out of it and reinstall.
:SOMBRERO:

I think the more stringent CA emission testing can catch a gutted cat, and maybe other states?

ebbnflow · **Posted:** Mon Jan 14, 2019 6:50 pm

I've been running T6 in my CRD since 2010. 5-6k OCI. I still have my cat and haven't noticed any performance difference over the last 8 years.

GordnadoCRD · **Posted:** Mon Jan 14, 2019 8:31 pm

Mountainman wrote:

I think the more stringent CA emission testing can catch a gutted cat, and maybe other states?

They didn't with me, Nick. They passed my van after the 3rd section fell apart and blocked the exit by sitting sideways to the exit pipe. They continued it pass it over the next 12 years after I pulled it out and gutted it. It always passed the "sniff" test, and had the proper ID plate, and that was all they cared about.

Regarding engine oil, since rebuilding the top end, until this last change I've used M1 TDT, and been having it analyzed each time.
This last change, I switched to Triax. https://www.amazon.com/gp/product/B07BBMWQS4/ref=ppx_yo_dt_b_asin_title_o03__o00_s00?ie=UTF8&psc=1
I don't expect it to be any better, but definitely comparable, and cheaper when bought in the 2.5gallon jug.

PZKW108 · **Joined:** Sun Apr 06, 2014 5:23 pm **Posts:** 461

flash7210 wrote:

Mountainman wrote:

Thanks for the info fellas, I guess it's probably not worth worrying about. But, IF the XSP is better, then maybe it's worth switching if you can get it at a good price. I'm going to see if my oil is darker than usual with the switch, maybe indication of a reduction of deposits

On any diesel engine, the oil is gonna quickly turn black from all the combustion soot.
This is a good thing.
You want the oil to hold all those microscopic carbon particles in suspension and not be deposited on all the shiny smooth rotating parts of the engine. (i.e. the roller bearings on the rocker arms)

Pretty much all the CK rated oils are the same.
The only differences are oil weight (10w-30, 15w-40, 5w-40) and base stock (conventional, synthetic, synthetic blend).
There are plenty of other silly details that are continuously debated over, but... :roll:

Note: some of your big diesel trucks include centrifuge filtration to remove the carbon particles form the oil.

Keep in mind that many of us have tune that considerably reduce EGR fonction or simply deleted the EGR...

I can drive 2500 miles with fairly clear oil. I wonder at some point if I really need diesel oil.

I use Liqui Moly 2332 Leichtlauf High Tech 5W-40 Engine Oil and I change every 5000 miles .

This and the equivalent Motul oil ( can't remember what one exactlly) are the best lubricant you can put in an small European diesel engine !!!

WWDiesel · **Posted:** Mon Jan 14, 2019 10:31 pm

Mountainman wrote:

WWDiesel wrote:

There is a simple solution if it is a Jeep CRD. Remove the CAT like many have already done and it becomes a non-issue.
It will not trip any DTC's and the Jeep will run better without the backpressure which lowers EGT's.
If you have to pass a visual inspection, remove the CAT, bust up and remove all the guts out of it and reinstall.
:SOMBRERO:

I think the more stringent CA emission testing can catch a gutted cat, and maybe other states?

Only if they put a sniffer up the tailpipe, and so far no one has reported them doing that on a Jeep CRD... :juggle:

Shell Rotella T6 not good for catalytic converters

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