I'm reeeeaaaally getting tired of Mobil's monkeying with their product line. The Delvac-1 formula changed... it is now "Delvac-1 ESP", with a CJ-4 rating. Click here for a photo of the jug and some more info. And, the Mobil-1 5W-40 "Turbo Diesel Truck" oil has also changed, it's got a spiffy new label on the bottle, and is also CJ-4 rated. Click here to see Mobil's website info, or click here for the data sheet.

However, I called Mobil and asked if the two were the same. Answer: No. They are NOT the same formula. The tech was unhelpful and didn't elaborate. And at first he didn't even know the M-1 TDT was reformulated, I had to convince him that I was looking at a new bottle with new ratings! D'oh!

Anyway, up until recently, the M-1 TDT oil was identical to the (original) Delvac-1 oil... same formula, same oil, different bottle. But it looks like that is no longer the case. If you are wondering what "ESP" stands for, it's "Emissions System Protection", where they have removed (or reduced) certain additives from the oil. Click here for more details. FWIW, I don't plan to use any ESP oils in my older (80's and 90's) engines. Now it looks like I'll be hunting for the "old" stuff before it vanishes entirely... *sigh*

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