CJ-4 is fully backwards compatible to CI-4 and CI-4+. The CJ-4 oil has less ash so it won't plug after treatment components in the newer diesels so the TBN is lower. This isn't a problem if you are running low or ultra low diesel in your tractor (500 or 15 PPM). It used to be a concern if you were running "off-highway" diesel of up to 5000 PPM sulphur as long as you adjust oil change intervals according to the TBN results of your oil (you'll need to run an oil analysis). There are some instances where you can still get up to 3000 to 5000 PPM sulphur diesel. The CI-4(+) products may allow for a longer oil interval. Burning this fuel it won't matter much which oil you use as it will still have to be changed on a much shorter interval than using low or ultra low sulphur.
CJ-4 disperses soot better than CI-4(+), more thermally stable and is also more resistant to oxidisation. This equates to extended oil intervals over CI-4 if you are using low or ultra low sulphur.
Short answer: CJ-4 is a much better oil. If you are using 500 PPM or less sulphur it is a no brainer.
