T6 bad for catalytic converts

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southernjeeper

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Since the crave of using Rotella T6 among a lot of people on here say it's good stuff to run in just about anything it seems. I tried the switch though I didn't find out whether I made the right move til after I did the oil change and had been running T6 for a week.

I personally emailed Shell and I got this response, "We do not recommend Rotella T6 for engines with catalytic converters."


So I guess for the week that I wanted to rotella before I got word back from Shell now just cost me the $20+ for the oil I bought.

Back to running trusty old Vavoline Maxlife in both the cherokee and the tacoma.


Wish I kinda sent the email sooner. I was a bit skeptical but went out on a limb to see about the T6...

I am anti-T6 now and I will leave the T6 for the diesels.
 
huh? It is API SM or SN, isnt it? What does your vehicle require? a '92 jeep should need like API SH or so.

Totally fine.

40wts will have a bit more zddp than 20 and 30 wt oils, but I dont see it as a big deal at all.

If they were saying Rotella T1 or something much more HD diesel oriented, I might understand.
 
If your engine burns a bit of oil then yeah! the elevated levels of ZDDP will gradually kill your cat and/or O2 sensor, end of story.

I know a lot of folks will say YMMV but in our area we have to go through emissions testings and I've seen CAT dies off far sooner than a properly maintained engine (that doesn't burn oil), and CAT will still pass emissions/functional abeit lazy.

We have local shops here doing brisk cat replacement biz a few years back since the implementation of mandatory emissions testing, but as the smoking automobiles gradually taken off the road, their biz died off eventually and now they are into something else (brake? quikkie lube, etc.)

Q.

Q.
 
Originally Posted By: southernjeeper

I personally emailed Shell and I got this response, "We do not recommend Rotella T6 for engines with catalytic converters."

Huh???

But it carries API SM rating, making it suitable for modern gasoline engines. I'm confused.
 
It is dual rated, I have used HDEO's for gas engine with no problems caused by the oil. Do you have the email from Shell and can you post it here?
 
I've run Mobil 1 5W-40 TDT (Mobil's maybe superior comparable oil) in my 2003 Saab 9-5 Aero since new, almost 165k miles. Original cat. Burns about 1 qt/5k. I believe the purported cat destroying capability of dual-rated oils is overstated. They are rated for gasoline engines after all.

jeff
 
This sounds incorrect to me as well. Like someone else mentioned the T6 is API SM rated for passenger cars so it passes requirements on cars that use catalytic converters.

Someone should e mail Shell back and clarify what they said.
 
Gulp! Just put t6 in an oil burner purposely last night! In an attempt to clean the engine.
confused2.gif
 
I just did some searching.. The difference between a SN rated oil and T6 is approx 400ppm of ZZDP?. Hmm..if I see a 50% reduction in the rate of consumption I would pass less ZZDP over the cat than I was with SN. I'm sticking with T6 till I find that out.
 
Originally Posted By: DemoFly
Burning oil in itself will kill a catalytic converter, I never understood this argument.


I agree... what about PCMOs with higher levels of zddp?

IMO if you tested a PCMO vs HDEO in relation of cat/o2 sensor life I suspect the results would be within the margin of error of each other.

my .02
 
Originally Posted By: southernjeeper


I personally emailed Shell and I got this response, "We do not recommend Rotella T6 for engines with catalytic converters."


So I guess for the week that I wanted to rotella before I got word back from Shell now just cost me the $20+ for the oil I bought.

Back to running trusty old Vavoline Maxlife in both the cherokee and the tacoma.

Wish I kinda sent the email sooner. I was a bit skeptical but went out on a limb to see about the T6...

I am anti-T6 now and I will leave the T6 for the diesels.

Could you post your email? I am also curious as to why you emailed them in the first place. T6 IS AN AWESOME OIL! I will use it in my Legend when its turn comes up as I have some 2 gallons still in my stash.
 
Originally Posted By: JHZR2
If they were saying Rotella T1 or something much more HD diesel oriented, I might understand.


Even then, good grief. All the modern dual rated HDEOs, including the conventionals, have the SM specification. Yes, the ZDDP might be higher than than what automakers would like to see.

However, this is a 1992 vehicle. The warranty is long, long gone. Back in 1992, there were plenty of high zinc PCMOs out there. I don't remember seeing truckloads of bad cats being hauled out to the local metal recyclers, either.
 
I'd email them back and ask why it would be detrimental for a cat in a gasser, but it's "recommended" for a diesel engine, all of which today also come with cats ...

I'd look at the prima facie evidence:
1) T-6 is SM rated (or maybe now even SN?)
2) diesels also have had cats installed for many years now

Me thinks the initial answer is incorrect.

Just because you email a source, does not mean you always get a good answer from a knowledgable person. At times, you have to use logic and ask follow up questions.


Of course, what they "recommend" would probably be one of their Formula Shell products. There is a big difference between what is "recommended" and what is "approved". The T6 is, to the best of my knowledge, API SM approved.
(this might be a cached version, but I do not see SN approval)
http://www-static.shell.com/static/can-en/downloads/shell_for_businesses/oils_lubricants/1-52.pdf
 
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It was just a PC, "don't sue me" answer. Southernjeeper, your '92 Jeep was designed for an SL oil and grew up with as much or more ZDDP than the the T6 contains, so really nothing has changed for it. It's true that ZDDP poison cats but it's relative to the amount of oil passing thru the cat. The difference is that today, the OEMs have been required to extend cat warranties on new cars and high levels of ZDDP make that harder to do. Plus, ZDDP is less necessary for the most modern gas engines so the new formulations reflect that. Back-specing is of secondary importance, so the owners of older vehicles should be aware that they might have special needs. Seems to me SN oils back spec pretty well but not in every case.
 
Originally Posted By: Quattro Pete
Originally Posted By: southernjeeper

I personally emailed Shell and I got this response, "We do not recommend Rotella T6 for engines with catalytic converters."

Huh???

But it carries API SM rating, making it suitable for modern gasoline engines. I'm confused.



So is the new formula of T6 is perfectly fine with gas engines then????

I just had found when I google'd that t6 might be bad for cat converters hence why I emailed SHELL from their site.




SO when it all boils down to is there is no harm to shorting out the life of a catalytic converter? correct?


I should have mentioned that I switched from castrol 10w30 to the T6 in just the TACOMA not the jeep yet. I am going to see about a good 4,000 or 5,000OCI on the truck.

As for the cherokee I will switch sometime this fall due to me driving the tacoma a lot more nowadays.

thanks for all the responses. I know I can trust a bunch of feedback on here than anywhere else.
 
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