Schaeffer Manufacturing Co. 0700CK4-012 SynShield Durability Advantage 15W-40 Diesel Engine Oil, 12-Quart Bottle (Pack of 12)

Used it for years in my gm crate works great

I’ve put 110k miles on my truck over the last three yrs and finally switched to Schaefer’s. She’s instantly running more smoothly than I remember before the wear and tear. Impressive stuff. Should’ve started using it BEFORE all those miles but this has definitely made a notable improvement.

After 2 hours run time its still clean.

Love this oil. Great quality

Great fuel economy, incredible oil!

Great product as always from Schaeffers

Good oil at a great price, well worth the investment as I plan on driving the tires off this thing. I was previously running Castrol Full Syn and switch. My idle oil pressure is now 10 PSI higher. I tested this on a brand new oil pump and used Castrol after replacement. Used Sheaffer on the next oil change and I am happy to see the oil pressure running hire..

As a retired Ford Technician I am very pleasantly surprised by this oil. I have ran Motorcraft and Valvoline for decades. But this oil is amazing actually picked up 2mpg in my 6.0 powerstroke with this oil. Now that I am planning to open my own shop this will be my go to Diesel oil and will run in my personal truck.

Travel between Texas and Wisconsin several times a year. This oil has out performed all others hands down. My 2013 F-350 is a happy machine. Mileage Increased also by a mile per gallon.

Great oil, from a trusted, and well respected manufacturer. Buy this CK-4 rated oil with confidence.