Rotella 10w-30: what changed?

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A few years ago I got a good deal on Rotella T4 10w-30 and picked up several gallons. I used it in both a diesel tractor and also in my 98 Chevy truck, since it was dual rated. I see now that T4 no longer carries an S rating. Did Shell change the formulation or did the specification change and make them drop the gasoline engine rating?
 
A few years ago I got a good deal on Rotella T4 10w-30 and picked up several gallons. I used it in both a diesel tractor and also in my 98 Chevy truck, since it was dual rated. I see now that T4 no longer carries an S rating. Did Shell change the formulation or did the specification change and make them drop the gasoline engine rating?
Look at my VOA and you can tell us. If anything did change aside from it not being SN and keeping CK4
 
Doesn’t it have to do with the amount of zinc in the oil? To be SN rated it has to be below a certain threshold and that’s not enough for Diesel engines if I recall correctly.

Just my $0.02
From what I understand, it has more to do with the phosphorous content of the oil. SN caps at 800 ppm and HDEO can be up to 1200 ppm or higher. There used to be a sort of loophole where dual-rated HDEOs like Rotella could have more than 800 ppm and still carry the SN spec, but that changed not too long ago. Now it has to have 800 ppm or less of Phosphorous to have the SN rating.

I read on another thread here that even though Rotella removed the SN spec from their labels, the formula didnt change.
 
It’s been my understanding that Rotella oils (T4, T5, and T6) did not change their formulation since dropping the gas rated spec.

Can’t help but wonder if it has something to do with them pushing the T6 gas/ diesel 5w30 oil, but they need to do something about the price before I’d consider it for my “fleet.”
 
In order for an HDEO to carry dual ratings now it must comply with the limits on phosphorous as the resource conserving S category it claims. This does not however mean that all S-rated oils have to be below the 800ppm limit. Only grades that can be resource conserving are limited, so a non-dual rated Straight grade, or 15W30, 20W30, 10W20, etc... or any Xw40 or heavier can exceed the limit and still claim an S rating so long as it doesn't also claim a C or F rating.
 
So does this mean I’m safe to keep using it in my gas truck? Sounds like it to my uneducated little brain.
 
For a production series (like the T4, T5, or T6 series,) each weight is going to use the same additive package.
Like said above, there is a limit on phos for the resource conserving weights (10w-30 included) for the API SN, SN+, and SP (also SM, i believe)
If they want to offer a product that is dual rated (between API CK4 and S-), then the formulation will have to conform to both specs according to the most stringent weight,

Shell decided that their T4 lineup should include a 10w-30 weight.
Shell decided that they wanted to continue using an additive package that had >800ppm phos.

Shell's Rotella T4 15w-40 product, specifically that weight, would technically conform to the API SM (and up) spec, because that weight in API SM (and up) has a looser limit on phos.
 
So does this mean I’m safe to keep using it in my gas truck? Sounds like it to my uneducated little brain.
It's essentially the same oil you've always used so, it should be fine, the only reason they reduced the phosphorous on SN was because it contributes to fouling of the catalyst and may shorten the life of a catalytic converter or contribute to reduced catalyst efficiency, the modern S-rating is about keeping a new catalyst as far above the efficiency threshold for as long as possible. If the car isn't consuming a whole lot of oil your catalyst probably won't see much difference between running a proper modern passenger car rated 10W30 and the t4 10W30.
 
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