BLACK OIL QUESTION

Muleskinner · Mar 4, 2006

I use Delo 400 15-40 in all of my Kubota engines, including my Dodge truck with a Cummins 5.9 diesel engine. I change my oil every 50 hours on the tractors. The oil in the tractors turns BLACK in less than an hour after changing the oil and filter. In the Cummins it takes about 1000 miles to turn the oil black.

Now I know all about the soot being trapped in the oil, Etc Etc. I just wonder why the Kubota engines turn the oil black so quick. I believe it's because the Cummins is a "Direct injection" engine, where the kubota uses an "Indirect injection" engine. My dealer's tech was unsure why the oil turns black so fast, but agreed the indirect injection may have something to do with it. It would be interesting to see if the oil in the new 2006 M series direct injection engine gets black as fast or stays cleaner longer.

What say you?

Egon · Mar 4, 2006

The oil in my Kubota turns black as soon as its changed.

On the Dodge Cummins the oil on the dipstick remains clean almost till it's time for an oil change. Course the oil comming out the drain is black.

Egon /forums/images/graemlins/grin.gif

ccsial · Mar 5, 2006

The oil on all 3 of my tractors turns black very fast. My Dodge Cummins never gets as black as the tractors.

JJT · Mar 5, 2006

In both of my Kubotas the oil takes at least 10 - 20 hours before it starts to turn dark. I'm running Rotella synthetic and change my oil annually, (80-100 hours).

Why not spend $10 and send a sample out for analysis? I bet at 50 hours your black oil has lots of life left in it. I use Oilguard for analysis. Before analysis I used to change my oil twice a year in the tractors and every 3000 miles in the cars. Now I'm annual on the Kubotas and 10,000 miles on the cars. Based on analysis I could easily go longer, but my current intervals are easy to remember.

Builder · Mar 5, 2006

Very interesting. So what you've found is that previous to testing, you were changing your oil much too soon/frequently?

We should all have such good information. The drain intervals seem to be increasing on diesel trucks.

_RaT_ · Mar 5, 2006

Good post John, I agree with you.

5030tinkerer · Mar 5, 2006

Has anyone tried Amsoil's new EaBP by-pass oil filter that supposedly filters out the soot? I am tempted to try on my next change. Have never used an Amsoil product, but am intrigued.

Av8r3400 · Mar 5, 2006

My VW diesels are the same as my Kubota. My old Chevy 6.2 was the same also. Oil goes black almost right away. My Cummins will stay "clean" much longer. I think it may have something to do with the "direct injection" on the Cummins. Maybe this just runs cleaner? Dunno.

Muleskinner · Mar 5, 2006

Well at least I know it's not just mine. Would be interested in hearing from anyone with the new M series direct injection engine after their first oil change.

cp1969 · Mar 5, 2006

( My VW diesels are the same as my Kubota. My old Chevy 6.2 was the same also. Oil goes black almost right away. My Cummins will stay "clean" much longer. I think it may have something to do with the "direct injection" on the Cummins. Maybe this just runs cleaner? Dunno. )

Unless you have old VW diesels, they are direct injection.

Ed_L295DT · Mar 6, 2006

I like and I believe in the oil sampling thoughts earlier. Who are we to know how black is black? Oil sampling eliminates this variable.

A direct injection engine burns cleaner than indirect engines. Couple this with frequent start ups and shorter run times and you may have more debris bypassing the (cooler) piston rings.

These comments come from forty years of repairing heavy construction equipment.

Av8r3400 · Mar 6, 2006

Best explination I've heard, yet.

(and yes, you're right, my '01 VW is a TDi - Turbo Direct Injection /forums/images/graemlins/blush.gif )

SeymourBota · Mar 6, 2006

Disclaimer: non-scientific reply!!!
One of my colleagues had an older Dodge Cummins and wound up replacing his engine with one that was 'built' as a test engine. He could put out nearly 1000 lb-ft of torque. He could also fill the entire town with soot, depending on how he tuned it.
My point is that our tractor diesels, as with his newer engine, are only concerned with power and torque production. Creation of soot is an acceptable buyproduct.
Diesels running the roads, especially these days, are expected to burn cleaner and are tuned to do so- apparently inside and out. Direct injection is a part of this.

equipman · Mar 6, 2006

Muleskinner
According to the manual with the new 40 series tractors, the oil change interval has been extended to 300 hours. This is after the initial change at 50 hours.
Lewis

_RaT_ · Mar 6, 2006

Not necessarily true. The Kubota diesel meets and exceeds the diesel CARB requirements here. That means regardless of the application, farm, stationary generator, construction equipment, Ag or boat, it all must meet the rules. It is a very clean burning diesel. The "soot" or black oil has little to do with the emissions as I understand. My old direct injected International had clean oil but was absolutley the smelliest diesel I have owned. I talked to my CASE dealer and he said thats just what old design will do. Todays pumps and injectors do a very good job of atomizing the diesel fuel and surrounding it with as much oxygen as possible. The next step will be cleaner diesel fuel which is already in the works.

kmdigital · Mar 9, 2006

Actually, the primary difference is that the Kubota engines all use mechanical fuel pumps and standard injectors, while the Cummins (and Powerstrokes) use electronic injectors and computor controls to MUCH more precisely control the timing and flow of fuel. The electronic injectors inject the fuel at a much higher pressure (upwards of 30,000 PSI), which also results in complete fuel atomization, and a cleaner burn. And the computor allows very precise control of the amount of fuel that is injected, which results in better efficiency and less unburned fuel (i.e. carbon) to turn the oil black. On my Powerstroke truck, the oil isn't even black yet at 6,000 - 7,000 miles, but on my tractor it is extremely black shortly after it is put in. Not to worry, that is just the way it is, and it doesn't take much carbon to make the oil completely black, and it doesn't seem to hurt the lubricity any.

I'm not sure what the mechanical injection pressure is, but I'm thinking it is something like 10,000 PSI, so you can see there is a significant difference. I live in the RV capital of the world, and the delivery companies around here won't hire drivers with diesels that don't drive late model diesel trucks because the older diesels smoke too much and make the RVs all sooty. Nobody wants their brand new 5th wheel to have soot stains on the front end and side.

SkyPup · Mar 9, 2006

The single orifice pintle injectors on the indirect Kubota engines only max @ 3,000 psi.

The only reason the oil turns black fast on some engines compared to others is how well the oil completely drains out of the oil filter housing, the oil gallerys, and the oil pan. The ones that don't drain all the oil well are immediately contaminated with residual black oil containing soot, the ones that do drain well aren't.

All my high pressure direct injection VW TDIs, indirect low pressure Massey Fergusons, and indirect low pressure Kubotas all turn black right away.

Black oil is good in a diesel engine, it means the detergents are doing their job well suspending the soot particles, I would be very concerned if it was NOT black! /forums/images/graemlins/blush.gif

cp1969 · Mar 10, 2006

( On my Powerstroke truck, the oil isn't even black yet at 6,000 - 7,000 miles, )
Be careful...I made the same statement about my Cummins and was challenged by somebody who knew what color my oil was despite the fact that he was 1,500 miles away.

( The single orifice pintle injectors on the indirect Kubota engines only max @ 3,000 psi.

The only reason the oil turns black fast on some engines compared to others is how well the oil completely drains out of the oil filter housing, the oil gallerys, and the oil pan. The ones that don't drain all the oil well are immediately contaminated with residual black oil containing soot, the ones that do drain well aren't.)
Amen.

( Black oil is good in a diesel engine, it means the detergents are doing their job well suspending the soot particles, I would be very concerned if it was NOT black! )
I agree, but apparently some of these newer engines just aren't generating the soot that the old ones used to. If the soot was there, but not suspended in the oil, it would have to be accumulating somewhere else, wouldn't it? I haven't seen any evidence of that. It probably has a lot to do with how hard an engine is being worked, too, and my engines have it pretty easy compared to some.

SkyPup · Mar 10, 2006

Any diesel engine with EGR is going to create more soot in the oil than one that doesn't have EGR. Also, any diesel engine with an old unchanged air filter will produce allot more soot than the same engine with a clean air filter.

Most diesels now utilize retarded injection timing to decrease NOx emissions, those with retarded injection timing will also create more soot that a diesel with normal injection timing.

Leaky injectors also produce allot more soot than injectors that are set at the correct pop pressure and don't leak.

Also, people in Texas and California running on ULSD will not produce as much soot either due to the fact that each soot particle has a sulfur atom at its core, the carbon precipitates around the sufur atoms, ie less sulfur in the fuel = less soot production.

Untaxed high sulfur diesel fuel produces allot more soot than taxed road diesel fuel, another good reason to change your oil more frequently if you use off road high sulfur diesel fuels....

5030 · Mar 11, 2006

Mr. Pup:

At least here in Michigan, the difference between "off road" and "on road" diesel, aside from the road use tax is only red dye.

All diesel sold here is LSD. 1-01-2007 will be ULSD. There is going to be a lot of leaky pumps in 2007 as well as scored injector tips.