mo1
Platinum Member
The manual has temperature- based recommendations for straight-weight oils.
— SAE 30 for 80F+
— SAE 20 for 32F to 80F
— SAE 10 for -20f to 32F
— (I am staying in bed if I need the SAE 5...)
What are you using for your tractors? The bulk of my use will hopefully all be above freezing...
Thank you!
Generally 15W-40 has been recommended as the replacement for older four-stroke diesel engines that originally recommended SAE 30. Deere specifically says in their documentation they recommend using 15W-40 in place of SAE 30. You could also use pretty much any diesel engine oil with a 30 or 40 as the second number (e.g. 10W-30, 5W-40, etc.). It just needs to be a diesel engine oil with an API spec starting with a "C" and not a gasoline engine oil with an API spec starting with an "S." If the bulk of your work is above freezing, I would just get a 15W-40 diesel oil.
The API has retroactively changed the oil specs from what they were in the past. The first ones were after WWII if I remember correctly, and they were ML, MM, and MS (light, medium, severe.) Diesel engines used MS and sometimes MM, gasoline engines may have specified any of of those. I believe in the 1960s they introduced the current-type "S" specifications for gasoline engines and "C" for diesel engines. 1960s diesel oil specs were typically CC or CD. Newer specs supersede older ones so somebody running a 1960 tractor could run about any diesel engine oil available today and be more than fine. The only ones who really need to look carefully would be people with Tier 4 tractors, running anything older than CJ-4 can kill the particulate filter and catalyst. I haven't seen anything older than CJ-4 in some time as that came out 20 years ago, and virtually everything now on the shelves for diesel engine oil is the latest CK-4 spec.
EDIT: The Case logo there is called "Old Abe." That went away in the mid-1960s but Case did fairly recently reintroduce a different eagle logo on their construction equipment.