How do these oil analyses look?

[bobk]

Engines are 425 HP 1980 6V92TA on 1981 Series I MY. Majored 650 hours ago. Figures below are for 175 hours running time, mostly 1000-1100 rpm with occasional run ups to 2000 rpm. Engine coolant temps hold 160-165F. Oil was Mobil Delvac 1240. Figures are from Staveley Analytical, Atlanta. Staveley does analyses for the DD sample kits too (mine came from NAAPA) and they say they have the DD specs on oil quality. They report 'no corrective action needed'. All comments appreciated.

component iron chromium molybdenum fuel water soot coolant TBN
port engine 106 11 7 <1 0 1.6 no 5.5

stb'd engine 88 3 4 <1 0 1.0 no 5.8

Bob
ps, sorry guys, I can't seem to make this into a table

 

[SKYCHENEY]

Delvac 1240 is actually the exact same oil as DD branded oil. Here is a part of the article from Pit & Quarry magazine that references just that:

For Detroit Diesel two-cycle engines, (i.e. Detroit Diesel series 53, 71 and 92 series engines - which are used in both over-the-road and auxiliary equipment, and in smaller equipment in the off-highway service market), Detroit Diesel recommends oil drain intervals of 15,000 to 20,000 miles or 300 hours. Detroit Diesel insists on a monograde oil with less than 1.0 percent sulfated ash, such as Mobil Delvac 1240, as well as its co-branded straight graded SAE 40 weight oil.

 

[Genesis]

Those look like good numbers to me!

 

[Top Shelf]

Oil changes at 300 hours on the mains!! Is that true? I've been doing em at 100??? And with a 5 gal bucket now at 75 bones,,,,,I'm all ears. Thx.

 

[REBrueckner]

I understand the DD standard for two cycle engines less than 5PPM for Chromium....rings, etc at 100 hours. (I don't have other data with me). So your port engine looks a bit HIGH...but don't panic.

You should search here at Sams for prior detailed discussions...Among them is my post that one thousand hours ago I had a Cr reading of 12 on one engine at about 75 hours, which went unmentioned, and a current reading last fall around 7, and comparable hours, which was reported by another lab as "elevated". So how could rings get better after 1,000 hours more use?? The point is you'll want to check and compare readings again at your next oil analysis...if that Cr reading creeps up, something maybe amiss...if it stays steady or decreases, I'd not be a worrywart...it's the trends over time that matter most.

300 hours: That's not the traditional interval for marine engines! I'd never let old oil sit in an unused engine over the winter season. On the other hand, one year I ran 200 hours, had the oil checked, and it was fine at the end of the season. But I changed it before winter shut down. If you are running regularly year round, have the oil analyzed at perhaps 100 or 200 hours and see what results you get...likely its fine...if not, change it.

By adding bypass oil filters, with steady year round use, you can get 1,000 hours and likely much,much more before change...ferries,for example, can get 10,000 hours (with oil top off due to consumption)... sample at regular intervals to assure compliance with specs....DD approves the use of bypass oil filters with analysis at regular intervals. But they don't pay with light use and with off season storage.

 

[SKYCHENEY]

Oil changes at 300 hours on the mains!! Is that true? I've been doing em at 100??? And with a 5 gal bucket now at 75 bones,,,,,I'm all ears. Thx.

That was in an industrial trade magazine, so I would assume that those figures relate to industrial rated engines, not marine. My point was just that DD brand oil is actually made by Mobil and is indeed the same product as their Delvac 1240.

 

[bobk]

Thanks for your thoughts guys. I'll check it again at the fall change and then settle to once a year after that.

Bob

 

[Genesis]

At that amount of running time I wouldn't be concerned with the chromium number. Especially if you don't run more than once a week.

Pull one next time you change and don't leave old oil in the engine during any winter lay-up.

 

[bobk]

Karl, we typically run about 400 hours a year. If you recall my posts and our PM's from mid last year, this is the boat that had a brief soot ingestion, but passed the 30 sec compression test and looked good in the air box examination on survey. The port engine (higher Cr) starts easier and smokes a bit less that the starboard. I'll reanalyze the oil in September and see if the Cr level has stabilized. I wonder what the variability of the analysis is. Would be interesting to check it if it wasn't so expansive.

Bob
Chateau de Mer

 

[Genesis]

I wouldn't call the Cr levels excessive given your running hours.... keep an eye on it.... you're probably ok.

 

[Boss Lady]

To be honest guys, oil analysis really only serves to alert you to high dirt levels, substandard oil quality, or early detection of coolant leaks. Even if you had high numbers on the wear metals, what are you going to do about it? Nothing, except wait until you have to do something due to loss of compression or something. So I just really look at the early detection of coolant leaks and nice to know information at best.

 

[REBrueckner]

Oil analysis variability: I posted on this subject during the winter....here on Sam's...I no longer remember the details and it's based in part of the equipment used for the analysis, but bottom line: it's very accuate...A search should turn up several threads of interest....What IS very variable is which readings get tagged by different labs...