1985 Merrcedes 300D, 5,900 mi., T5 10w30

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The first UOA I've done on an OM617 or this oil - very pleased! Also reaffirms my hunch that 40 weights aren't a necessity in these engines like a lot of the owners preach. This OCI had a pretty varied operation schedule - lots of short trips, 1000+ miles of 70-80 MPH highway running, and a few stints of very spirited backroad running.


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Originally Posted by Alex_V
The first UOA I've done on an OM617 or this oil - very pleased! Also reaffirms my hunch that 40 weights aren't a necessity in these engines like a lot of the owners preach. This OCI had a pretty varied operation schedule - lots of short trips, 1000+ miles of 70-80 MPH highway running, and a few stints of very spirited backroad running.

You do realize however that since this oil carries MB-Approval 228.31 has a minimum HTHS of 3.5? As a result the difference between a 30-grade and a 40-grade designation is a bit meaningless in this instance.

Rotella calls this oil "low HTHS" but that is in reference to some of their other oils and for some of the competition, it's not exactly low HTHS in the overall scheme of things related to passenger car diesel oils.
 
Originally Posted by Alex_V
and a few stints of very spirited backroad running.

What do you consider "very spirited" lol. I got one of those cars stuck in the pothole in front of my work.
 
Originally Posted by kschachn
You do realize however that since this oil carries MB-Approval 228.31 has a minimum HTHS of 3.5? As a result the difference between a 30-grade and a 40-grade designation is a bit meaningless in this instance.


How so? (Inquiring, not doubting.) It's supposed to start out at a 12, and most 40 weight diesel oils I've looked at are ~14-15.
 
Originally Posted by kschachn
Originally Posted by Alex_V
The first UOA I've done on an OM617 or this oil - very pleased! Also reaffirms my hunch that 40 weights aren't a necessity in these engines like a lot of the owners preach. This OCI had a pretty varied operation schedule - lots of short trips, 1000+ miles of 70-80 MPH highway running, and a few stints of very spirited backroad running.

You do realize however that since this oil carries MB-Approval 228.31 has a minimum HTHS of 3.5? As a result the difference between a 30-grade and a 40-grade designation is a bit meaningless in this instance.

Rotella calls this oil "low HTHS" but that is in reference to some of their other oils and for some of the competition, it's not exactly low HTHS in the overall scheme of things related to passenger car diesel oils.


+1.

Straight 30wt oils have always been allowed in certain temperature ranges.

The matter of 40wt oils is more about getting the right diesel-specific add pack, and a good level of ZDDP in there for these (somewhat) flat tappet cams.

Im interested to see how low the soot loading is for this duration.
 
Originally Posted by Alex_V
How so? (Inquiring, not doubting.) It's supposed to start out at a 12, and most 40 weight diesel oils I've looked at are ~14-15.

This might help:

https://360.lubrizol.com/2019/Visco...s-the-Difference-and-Why-is-it-Important

HTHS is a better indicator of the oil's actual performance in use and it is what the approval dictates as a requirement. This is another reason why approvals are important and significant.
 
Originally Posted by JHZR2
Im interested to see how low the soot loading is for this duration.



The "fuel" value at the bottom is the indicator of soot loading, yes? I know the primary limitation of OCI's in these IDI's is soot loading. It would be on the high side of its potential since a good 30-40% of the hours on this oil was low-speed town driving in cold weather, with many trips under 5 miles. This engine has about 7,000 mi. on new injectors and rarely smokes enough to be visible in daylight even when looking at the tailpipe. A good portion of this interval also had a consistent dose of Hotshot's EDT in the fuel tank.
 
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I have Rotella Diesel 10w30 in my 76 300D. WOT is practically the only way to drive a 300D
 
That Hotshot stuff is what I use. I think it is really good stuff. I have used it for over 2 years when my mechanic told me he used it and it has worked great for both of us. It should work great for you also! I also think you could go about 10,000 miles on your 10w-30 diesel motor oil. The limit is 2% soot for Mercedes. I went 15,000 miles on Amsoil 14w-40 diesel motor oil (AME) the soot level was 1.7%. This was on my 1984 300sd. I went 6110 miles on my 1983 Mercedes 240d and the soot level was 1.2%. The oil was 5w-40 T6 by shell. Maybe you should try using a UOA and then know for sure. I went 15,000 miles on my 1995 e300d with Amsoil 15w-40 AME diesel oil and the soot level was .2%. Of course, that car has a different injection system! Take care! Bill
 
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