For those of you who do not already know, I was able to find Mobil 1's 0W/40 at the local Autozone.

 

I am a bit wary of of th 5W/40 because of reports that it is repackaged Mobil Delvac 1 diesel oil that may, in the long term, contaminate the catalytic converter.

It has been established on BITOG that while Delvac and Truck and SUV are similar, they are not the same oil.

...Mobil Delvac 1 diesel oil that may, in the long term, contaminate the catalytic converter.

I would not be so sure. Delvac 1 is SL rated as is your 5W30 or 10W30 "gas" oil. True, it has more phosphorus (anti-wear additive), but the 0.1% cap to prevent catalist poisoning applies only to XW30 oils and thinner. XW40 and thicker oils are burned less by engine and thus are permited to have more P (0.12 IIRC).

If I was that worried about catalyst poisoning, I would drive low-sulfur gas only. Sulfur poisons catalyst short-term (partially reversibly).

I had thought about this point that higher viscosity oils result in lower consumption. With a synthetic oil, I suspect that these last line of defense additives almost never come into play at normal (sane) operating conditions.

 

What oil companies sell high sulfur gasoline?

 

It has been established on BITOG that while Delvac and Truck and SUV are similar, they are not the same oil.

Great website; I had never looked at this one. All my info. about motor oils has come from motorcycle websites, where the emphasis is on those without friction modifiers, which reputedly causes wet clutches to slip. Almost all motorcycles do not have a catalytic converter so I've been running diesel oils in mine for years.