For years I have been changeing oil at 12-15k, per what the engine/truck manufacturer recommends. Even when Speedco came along with "on site" oil analysis, I was dumping the oil, then reading the results of the analysis afterchangeing the oil. When I finnally read the results, I came to the conclusion that there was no reason to have changed it! By this I mean there was no abnormal wear metals present, soot levels were good, viscosity good, TBN# well within limits, etc, etc. I'm not using any exoctic oil here, just good 'ol Rotella t. Engine is a 3406E w/450k in normal use. Since I have an APU, I seldom idle.

For the past two years, instead of just pulling in, and letting them dump the oil, I've been requireing them to take an oil sample and analyise it before I make the decision to change it or not. I kid you not, at 45k, the oil has been well within tolerance everytime. I'm sure the lack of idleing has a lot to do with this, and the engine itself is obviously in good shape.

Normal PM oil change has been running me about $230-260 with cat filters, the other day I went in and had an analysis done, installed new fuel filters, and greased everything. (didn't need oil changed) $67. Obviously saving a few of my hard earned bucks, in fact quite a few over the 2 yrs I've been doing this.

Just thought I'd share this plan with u'all, see what ideas you might have. I might be doing something wrong here, but I'll be danged if I can figuire out what it might be.

Questions might range to warranty? In my case doesn't apply, engine is over 5 yrs old.
Just for giggles, I"ve had Speedco test new oil to check thier equipment, seems to be accurate everytime.

Your thoughts??

 

IMO, you have used the proper method of determining oil change interval (granted, that speedco's testing is valid).

The only question I have is: how long do you think you should leave your oil filter on the engine? It may need to be changed out before the oil does... it's bad news when the oil bypass valve opens due to a clogged filter.

 

bob That one of my concerns also. At 45k, I was showing a soot level of under 1PPM, 4PPM is the acceptable level. Seems to indicate the filter was still doing it's job. Question is, how much more capacity remains??

A sharp rise in soot levels would indicate it's reached it's limit but I don't intend to go that far.

Don't get me wrong here. I don't skimp on maintenance. I'm a retired CWO with a martine engineering background. As such I used oil analysis in the Army for years. The policy over there was "don't change it until the results of the analysis indicates the usefull life of the oil has been used."

Little tricky determining where that "usefull life" ending is. But I think most owners are probably dumping oil for nothing other than possibly "peace of mind".

 

Soot particles are too small for conventional, spin-on filters (0.5 microns), that's why diesel engine oil turns black almost immediately after starting an engine with fresh oil. Mack uses a centrifugal filter on their engines for this reason. I only bring this up because I don't consider soot levels relevant in many applications. Soot-loading is not really an indicator of the oils life, rather it is an indicator of engine problems, e.g. - an overfueling fuel injector would raise soot levels.

The base # is very important... your crankcase is a very acidic environment, and the only defence is your engine oil which neutralizes acids as long as it has a decent TBN (total base #).

The filter manufacturer should be able to give you a guideline for filter replacement based on your filter make and filter part #. For example ; a fleetguard LF3000 will likely have a better/longer service life than a bottom-of-the-line aftermarket filter that "FITS". Check their website, fleetguard has tons of good info, but the timeline will only be relevant if you're using their filter/#. If you're using CAT filters, check with them, if you're using DDC filters, check with them... Luberfiner, Baldwin, Donaldson, etc, etc.

 

Most conventional primary (full flow) filters filter between 100 and 10 microns, the secondary (usually by-pass) filter brings you down to between 0.1 and 1.0 microns.

You are doing right to still change filters at the recommended interval...hopefully you add enough "fresh" oil to compensate for that dirty stuff thrown away with the filters. As long as you still get good analysis results I would feel comfortable running a quality oil for 500k (and some go for 1M).

An added advisement...invest in a good after market add-on filtration system...always a by-pass...some are centrifugal some have specialty ultra micro media but either way it will help with the soot build-up issue, lengthen the life of the oil further and also give you some asses peace of mind....

I can't think of the name of any off hand but the magazines are chocked full of ads for them....just remember to do your homework!!!

 

Current H/D full-flow diesel oil filters remove particles between 25 and 60 microns. Bypass filtration (excluding centrifugal) filter down as low as 10 microns.

High efficiency fuel filters don't even go down to 1.0 micron absolute!?! Never heard of any filtration that gets down to 0.1 micron rating, at least not in the truck world.

 

At 45K, the tbn #indicated the oil had about 75% remaining, I was watching it closely.

Haven't done a thing to the engine. Just useing CAT filters all around. Single full flo filter, no bypass.

On the heavy duty diesels I used to operate/maintain, we used high capacity centrifuges to remove soot/contaminates. From what I can see with this engine, I would see no practicle gain from the use of any of these devises.

I wish I'd kept better track of this oil w/o the use of the APU, but I installed it when the engine had only 100k on it. Idleing would probably "kill" this oil in no time. I doupt if my idle time is more than 5%.

 

What do you mean by; I was watching it closely? How often do you draw a sample for analysis?

Approximately how much does it cost you for your oil analysis program? I'm just curious of the cost savings potential.

I agree that centrifugal filters are not practical, I'm wondering why mack (MBE as well?) feel they're necessary?

I personally believe that soot particles are not too damaging to engine components. IMO.

 

What I meant by "watching" the oil was that I was analyising the oil every 12kmi or so.

Since the truck needed a chassis lube and fuel filter change at that time anyway, I'd just pull into to Speedco, have them draw a sample, and while they performed the lube and filter change, wait for the result of the testing. If it tested good,(which it always did), button her up and head out. Cost for the oil analsys, $19.95!. I am leased on with Landstar, which through thier LLCAPP program offers free testing at every PM service.

I agree that a certain amount of soot contamination will do no harm. In excess amounts, you'll start to increase the viscosity of the oil. It's my understanding that the newer engines w/EGR have problems with increased amounts of soot contamination also. That would explain why newer engines are coming out with bypass filtration, centrifuges, etc.

Google in "soot contamination in diesel engines", all kinds of info avail.

 

Did some research on what a couple of you were talking about, soot size, filtration etc.

Average soot size, 15microns and below.

Average full flow filtration, 15 microns and above.

Average bypass filtration, 1-10 microns (and below if you want it)

Based on this info, yes, I could strain out some of the soot by adding a bypass filter, but based on the testing info, there is no need to that, as the soot levels have never reached anywhere near what would be detrimental to the engine, even at 45k.