Is high moly harmful to the Cat?

[MikeySoft]

Is high moly harmful to the Cat?

I remember reading on here that someone felt high moly is harmful to the Cat. I cannot find it now or any other mention about this possible problem. Is this true?

I feel it cannot be too harmful when the oil is gf5 and SN like the new Mazda 0w20 high moly oil.

 

[Hyde244]

If your oil is SN, it is the best oil for catalytic converters - that was one of the big focuses in the jump from GF-4 to GF-5 (or SM to SN).

 

[MikeySoft]

Thanks for verifying what I thought.

 

[Clevy]

It was likely skyship who posted the too much moly,I'm betting he got it confused with zddp. In fact I'm sure of it. I remember the thread. He went off on a tangent stating that no leading manufacturers top oil uses moly,and specified Amsoil however he obviously didn't get the memo because I found the new SSO sample and it did have moly.
Considering the source of the comment it carries no weight whatsoever.

 

[JHZR2]

Things that are harmful to the cat are compounds that can turn active metals to some kind of inert compound.

So things like Phosphorous and Sulfur are the issue, because they will create under high temperatures some funky stuff like phosphates and sulfates of and/or on the metals.

Of course, metals like lead, zinc and moly could coat the surfaces, and given that catalysis is a SURFACE effect, these could clog or coat the active materials.

 

[LeakySeals]

If you have an oil burner, stick with SN. If your not consuming any oil, use whatever oil or additive you want.

 

[uart]

If sulfur is harmful to the cat, then why not MoS? (Molybdenum - Sulfide)

That being said, if you not burning any oil (or hardly any) then SN or SM or SL or added MoS probably makes no difference.

 

[Trav]

I don't know but there is a lot of fear mongering going on with this cat damaging business.
I see cars everyday with 200K and more miles and 15+ years old with the OEM cat still working properly. I guarantee you they were not running SN in 1996.

I can tell you from years of monitoring over 1200 emission repair facilities for the state that most cats are damaged by overheating.
This can come from running way to rich for any number of reasons including a high misfire count.

Keeping the ignition system in top condition and running a bottle of PEA based cleaner every 3-5K will go a lot further in keeping the cat healthy than whats in the sump.

 

[pbm]

Originally Posted By: LeakySeals
If you have an oil burner, stick with SN. If your not consuming any oil, use whatever oil or additive you want.


I agree.
Running an SL oil in a newer car that calls for SM or SN shouldn't be a problem if the car does not use oil. I have considered running GC 0w30 (SL rated) in my Cruze turbo because it doesn't use a drop of oil (and I have 10 qts. to use up). It should be a good match for the (Opel designed) motor......after warranty of course....

 

[stranger706]

Originally Posted By: Trav
I don't know but there is a lot of fear mongering going on with this cat damaging business.
I see cars everyday with 200K and more miles and 15+ years old with the OEM cat still working properly. I guarantee you they were not running SN in 1996.

I can tell you from years of monitoring over 1200 emission repair facilities for the state that most cats are damaged by overheating.
This can come from running way to rich for any number of reasons including a high misfire count.

Keeping the ignition system in top condition and running a bottle of PEA based cleaner every 3-5K will go a lot further in keeping the cat healthy than whats in the sump.


+1

The only time I ever saw a cat go bad was about 12 years ago in college. My buddy's truck had a thermostat stuck open that was causing it to run cold all the time, which resulted in a rich condition and damaged the cat. He ran it like this for over a year before any exhaust symptoms showed up.

 

[MikeySoft]

Thanks for everyone's input.

 

[MolaKule]

Quote:
Is high moly harmful to the Cat?


Neither moly in MoDTC form nor Antimony in SbDTC form are harmful because they are dithiocarbamates with little sulfur content and they do not contain phosphorus.

 

[uart]

Originally Posted By: MolaKule
Quote:
Is high moly harmful to the Cat?


Neither moly in MoDTC form nor Antimony in SbDTC form are harmful because they are dithiocarbamates with little sulfur content and they do not contain phosphorus.


What about MoS, like the liqui-moly type after market stuff. That's the one I"m interested in knowing about. Do you have any info on that one MolaKule?

 

[[RT] ProjUltraZ]

i'm more worried about coating my spark plugs than the cat - but i dont have to pass emissions