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Schaeffer's API Service Category CJ-4 is for use in high-speed four-stroke diesel engines.

It is designed to meet 2007 model year on-highway exhaust emission standards as well as for previous model years. Schaeffer's oils are designed to exceed the CJ-4 category requirements. 

Please note: This category is mostly being replaced by the newer CK-4 Schaeffer’s SynShield® engine oils. Schaeffer’s Supreme 9000 5W-40 is moving into the CK-4 category and has a new name.  Schaeffer’s SynShield® OTR Plus Full Synthetic.  Even with the name change it is still the same product (and part number #9000) as the previous Supreme 9000. 

SynShield™ #700 Durability Advantage, #711 OTR Plus and #722 Ultra Performance oils meet and exceed the Ford WSS-M2C171-E and WSS-M2C171-F1 and are approved by Ford. All Schaeffer’s SynShield® engine oils all meet and exceed API CK-4, CJ-4, CI-4, CI-4 Plus and older.

Click here to shop the CK-4 Category.

Here are some real reviews from our customers:

Schaeffer oil. Your Schaeffer oil is an excellent product and online ordering could not be easier! James H.

Power stroke oil This is probably the best oil for the demanding 6.0 Ford power stroke. Easy winter startups has me sold on this oil. Magnus E.