Only for that darned inspection.
On a side note if you read the Motor Oil Bible he says "Current API specifications limit the amount of phosphorous in certain weight oils (0w20, 5w20, 0w30,
5w30 or 10w30) to .10% or 1000 ppm (these are one and the same). This is done because some
manufacturers believe that high levels of phosphorous will prevent catalytic converters from doing their
job for the full 150,000 miles that the EPA requires.
The problem with this theory is that this is only a problem when the oil burns. If the oil doesn't burn, the
problem really doesn't exist. That's where the NOACK (which we've already talked about) comes in. As
I've already indicated, most synthetic oils have NOACK scores that are half what their petroleum
counterparts are.
Studies indicate a direct correlation between the NOACK, oil consumption levels and the amount of
phosphorous that ends up leaving the engine with exhaust gases. So, logic indicates that a synthetic oil
with half the NOACK score and twice the phosphorous would cause no more damage to a catalytic
converter than a petroleum oil with twice the NOACK score and half the phosphorous. So, low NOACK
oils can increase their levels of ZDTP without harming catalytic converters.
In this way, the wear properties of the oil, as well as the oxidation and corrosion inhibiting properties,
can be increase significantly. However, this means that an oil which utilizes these higher ZDTP levels
cannot be "certified" with the API. It can be tested and shown to meet all other relevant criteria, but the
API will not certify it."