Toyota does not recommend MMT- really an issue?

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Jan 2, 2004
Colorado Springs
Just when I thought it good to use a small amount of MMT for valve recession, I noticed that in the 2004 Corolla Owners manual under fuel section(page 147),they say it may damage the emission control system and cause the malfunction light to come on.

Did I read to much into Molakule's comments about MMT? I had been using a slight amount(2oz) at every fillup.
What's MMT?

No matter what it is, if Toyota specifically says to not use it you'd better not unless you enjoy buying emissions parts. :)
MMT supposedly reduces the life of the now longer lasting emissions components. Its commonly used by Canada(?) hence the reason they say to always top off gas prior to visiting.
Instead of MMT as an octance booster, we use MTBE which helps destroy our water wells......
I guess that the MTBE lobby beat the MMT lobby in the US.

Originally posted by unDummy:
Its commonly used by Canada(?) hence the reason they say to always top off gas prior to visiting.

Who says this? I've never heard such a saying. I think our MMT limits are slightly higher, but within the max. limits set. It's not like our cats are failing at or two tankfuls ain't gonna hurt either....

I really don't think there's enough MMT in Outlaw to ruin anything, but if Toyota thinks it may affect the emission system, then don't use it.

The mix I described using MMT/FP/Neutra/Ethanol was recommended for older vehicles and racing engines.

The FP/Neutra mix alone was recommended for daily drivers.

Almost every OTC octane booster on the market contains MMT.
And i thought the reason that manganese was found in Canadian UOA was because the pump gas had MMT in it.

So no driving a 2004 Corolla in Canada?

The manual for my 2000 GMC Sierra pickup also warns of this too.

MMT (Methylcyclopentadienyl Manganese Tricarbonyl) is pretty toxic in even low doses and does appear to accumulate in the environment. In Canada it's made by The Ethyl Corporation, the same fine folks who told us leaded gasoline was GOOD for us.

CBC's consumer show, MarketPlace, had a very good blurb on the dangers of MMT in gasoline. You can visit:

and search for MMT.

Not only is the byproduct, manganese, toxic, but it may dramatically shorten the life of O2 sensors and catalytic convertors.

I'm not sure if MTBE had negative effects on the car, but it sure had bad effects on us too. You can't win.

Though as a typical "Canadian Compromise" we have MMT: it's bad for the car AND bad for us!

According to the automakers and other studies, MMT does reduce the effectiveness of emissions controls over time. Various studies have shown that results in higher emissions from vehicles buring gasoline with it than without.

Since automakers are forced to offer emissions warranties, it is in their interest to warn against using fuels that would degrade their life expectancy. Of course, this is tough to do in Canada, where most refiners still use it. Another case of change is hard and more importantly expensive! Changinr refineries to produce gasoline without costs money.

Contrary to popular belief, MMT is not illegal to use in gasoline in the US. That being said, it is not encouraged and because of clean air mandates, and refiners have alreay figured out how to refine gasoline with sufficient octane without it. Refiners are leery of it here because they fear the legal reprecussions of using it and finding out later its bad stuff.

As far as the MTBE lobby beating out the MMT lobby, I doubt it - they serve two different markets. MMT is the octane booster. MTBE is an oxygenate that reduces cold start emissions.
After a falst start a year ago, California finally got the MTBE out of the gasoline supply. Gas still stinks, though. Anyone else here old enough to remember when gasoline smelled "good"? (Not the same as saying gasoline was good to be sniffing, but it was, nevertheless, pleasant smelling. Now it smells like it's blended with stinkweed concentrate...)
What I'd like to know is what's used to get 98 Super in Germany (and Australia?) if we can only manage a meager 91???
No haven't forgotten...that's all I use. But, I'm wondering how do they get at that they just slap in a bunch of MMT?? Would going to a lower grade add life to the emissions equipment?

As a side note...just got a reply from STP. They do NOT use MMT in their Octane boost product. But, rather "Aliphatic Petroleum Distillates, Light Aromatic Solvent Naphthe, 1,2,4-Trimethylbenzene, 1,3,5-Trimethylbenzene, Xylene, and Naphthalene".
I don't think you'll find valve recession to be an issue in a 2004 Corolla engine. You're better off without the MMT for reasons stated above. If you're stuck using it because of a location, that is one thing, but I'd never add it intentionally.
Have you forgotten about Sunoco Dr.T? We can still get 94 octane from them.

I think the way they rate octane is different in Germany, so their 98 octane is possibly equivalent to our 94 octane.
Yes, Europe has a different scale for gasoline octane -- their 98 octane [RON?] is sort of equivalent to our 93 [(RON+MON)/2].

And as for filling up before entering Canada, I've been told to do this as well... by my Canadian friends!

Not so much to avoid the MMT, but mostly because gasoline is cheaper in NY.

Have you forgotten about Sunoco Dr.T? We can still get 94 octane from them.

Not in my state. All the Sunoco's decided it was a good idea to stop carrying the Ultra 94, and instead add 91 octane to the lineup, so now the 91 octane is "premium" and the 93 is "ultra". They charge the same price for the 93 as they were for the 94, too!
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