Thread: WILL The New AMSOIL (DEO) CJ-4 Premium Diesel Oil Truly Protect?

It will not hurt a thing for you to make the switch. Although the 5w-40 has better cold flow properties than the 15w-40, it also protects extremely well in extreme heat conditions as well as the 15w-40. I don;t personally believe you will have any issues at all, that is why I did not mind testing like this, I highly doubt there will be any major issues.

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Ok, I have an updated oil analysis report to add to this thread. The original question that I kept seeing come up in the past was whether or not the new CJ-4 rated oils would protect against Acid build up in the oil in the older model trucks that do not have a DPF due to the lower Total Base Number (TBN). I have no doubt that they protect as well as the higher TBN versions of synthetic oils in general, but I have to admit that originally I had my doubts. But, in the search for the truth I decided to test my results by running the new CJ-4 5W-40 (DEO) in my LB7 model Duramax.

To start with the oil looked to be doing a good job, testing after a 4-5K mile season hauling Christmas trees this past year. But, since then I have put another 10-11K miles on the oil and decided it was time to test again. The only difference in the truck between the two tests is that during the hauling season I was running what I thought was a stock tune. I later found out in February at the Georgia Diesel Dyno day event that the ECM had a crude tune that was also causing an over-boost code. So I had Harley, the owner of Georgia Diesel tune my ECM with EFI Live. He asked what kind of tune I was looking for and I asked for a respectable street/race tune that would not blow out my turbo or head gaskets. This was done and it went across the rollers for a three run average of 465hp and 857 ft lbs of torque.

I have to admit, I was excited to see the results on the dyno considering that the only other modifications to the truck are a dual disc clutch from south bend, a 4 inch straight piped Diamond Eye Exhaust, and a FASS lift pump.

Since the truck was tuned, I have had fun with the truck to say the least. I have had the opportunity to race three Mustangs, three Powerstrokes, two Cummins and a brand new Corvette CTS. The only one that I lost to was the CTS and even then it was not bad enough to say I was spanked. But anyway, I have had a tendency to beat on the truck pretty hard. This I believe MAY be a good reason for the higher iron and copper numbers in the report below. I have been told that higher rpm runs may or may not have this kind of effect on the engine itself if the oil is protecting properly, but I am about to test that theory.

Higher copper levels in the Duramax can be attributed to oil cooler leeching, but I have never seen numbers as high as mine in such a short time so I am leaning toward excessive wear on the internal engine parts. I will be contacting others in the industry with more experience than mine to help me troubleshoot this theory in the coming days and weeks, but while I do please note that I have decided to switch back to the 15w-40 Diesel & Marine Oil from Amsoil to see if I continue to see the higher levels of copper and iron as I have seen in the sample below.

Please note that every truck is different and there are many different factors that weigh on engine and lubricant performance in general. However, until such time as I have opportunity to do another analysis at around 3-5K miles with the new oil in the truck I will have nothing to compare to. But for now you can see what my results have been so far in the analysis below.

I CAN say that if you look at the TBN and Acid numbers, the 5w-40 CJ-4 oil held up quite nicely and other than the higher copper and iron numbers there is nothing really overwhelming to point to as a reason for saying that the oil will not hold up in the older model trucks. Once I have an analysis done on the fresh oil change I will have the ability to show whether it protects against excessive engine wear as well as the higher TBN oils.

Stay tuned for future oil analysis postings.

Current Analysis Results

very nice chris! thanks

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Just flushed the power steering fluid and changed the oil today. The power steering fluid was easy and quick. But of course with the oil I ran a flush and I generally run that for 20 minutes for good measure. I did not drop the pan, I was fighting rain intermittently so taking the time to drop the pan just wasn't in the cards. But I allowed 45 minutes for draining through the plug and the filter housing while having the passenger side of the truck in the air so that the oil was draining downhill. This is not a way to get ALL of the old oil out but it will allow a good amount of it to drain.

I am going to run this oil for 3-5 thousand miles and test another sample to see if I get similar results as in the last analysis report. I also want to see if the iron and copper go up or down with the new oil and filter.

Stay tuned for future updates.

An update to this situation, I have changed back to the 15w-40 Diesel and Marine oil. I found that with the continued use of the CJ-4 oil the wear metal numbers continued to climb and the TBN and Viscosity numbers continued to fall. Apparently the oil does not hold up as well over extended intervals as does the D&M. I have noticed that on other sites where these issues have been discussed the consensus is the same, although the new oils did quite well in laboratory testing, in the real world applications they tend to break down much easier than expected. As a result, I am now ONLY recommending that those people that have a DPF equipped truck run the CJ-4 rated oils due to this break down issue.

Hope this helps!

Thats good to know. Thanks Chris!