Diesel Oil Questions

[DavidWSnow]

I am upgrading my RV to a 2005 Country Coach Inspire with a 400 HP 8.8L Cat C9 engine that takes 9.25 gallons of oil per oil change. I live in Seattle and typically drive the RV about 5,000 miles a year, mostly here in our very temperate, but wet, climate.

I asked for an oil recommendation from the local Cat dealer and they suggest conventional 15W40 API: CJ-4 changing it every 10K or 6 months. This makes oil changes a significant expense at twice per year.

My diesel repair shop charges $6 per quart for conventional, but will install Rotella T6, if I provide it. Since Walmart sells T6 for $22 per gallon that makes it cheaper than conventional oil for me. Still that is $220 of oil plus a filter per change.

I have always been confused about the time limitations on oil changes. Oil isn't like milk - its doesn't have an expiration date on the bottle. What causes the additives in the oil to wear out or dissipate so quickly just sitting in my oil pan without the engine running much?

Wouldn't regular 6 month or 12 month oil analysis be a better, and cheaper, way to figure out when to change my oil? Assuming that I got an extra 6 months between oil changes it would be cheaper as well.

In Seattle, it rarely gets to the single digits in the winters, and we usually only have 5-10 days in the 90s in the summers. 100 miles east it is much more extreme. Wouldn't T6 (5W40 API: CJ-4) be better for my engine than the 15W40 that Cat and Cummings like to recommend for engines this size?

Answers to the questions in bold would be appreciated.

 

[Donald]

I see no need to use anything more than Rotella T 15W40. Its $12+ at Walmart/gallon and I think you can get it cheaper at Walmart in larger containers and/or cases at Sams Club.

Change it once a year.

Do a UOA for its first oil change with Rotella T.

Rotella T worked very well for my Cummins and now going to T6, but I will run that 15K maybe 18K.

 

[eljefino]

Originally Posted By: DavidWSnow
What causes the additives in the oil to wear out or dissipate so quickly just sitting in my oil pan without the engine running much?


Sulfuric acid, from the sulfur in gasoline and the water vapor from combustion. Typically from short-tripping it daily not going for occasional road trips then parking for a while.

But... wait... you don't have gasoline, so this doesn't apply in any shape or form!!!

Absolutely analyze your oil before dumping it. See what the bus companies and OTR trucks do.

 

[zzd]

Why not use T6, and keep it there for a year, and then do oil analysis on it, and see how it works out.

More information might be helpful, for example, do you make many short trips, or does your engine get started twice a year for a long trip?

If you are going for a longer change interval, the incremental cost of the T6 over T, is negligible, which is why I suggest the T6.

 

[Ramblejam]

Originally Posted By: DavidWSnow
changing it every 10K or 6 months. This makes oil changes a significant expense at twice per year


http://www.rvtechlibrary.com/engine/Cat_C9_Specs.pdf

PM Level 1 Recommended Change Intervals
Oil Pan - 32L (34 quarts)
20,000/1 - Miles/Years with Scheduled Oil Sampling (S•O•S) analysis

 

[bullwinkle]

I see your engine has no DPF, so first thing I would do is locate a source for oil in a 5 gallon pail-2 of which would do an OC, preferably a CI-4 oil (such as Delo 400 or Valvoline Premium Blue Classic) which is better for neutralizing acids in the oil from condensation & combustion. Then pick up a sampling kit & test kits from Blackstone or similar, and see what your actual oil condition is after a year or so. I have a load of CI-4 Mobil 1 Turbo Diesel Truck that has been in my Ram for over 3 years and roughly 9500 miles-and testing has shown that it is still OK for continued use!

 

[Chris142]

I let my petetbilts oil go 3 yrs and blackstone said it was still good. I change my boss' oil in his motorhome every 2 yrs which is only about 6k. His 3176 cat holds 8 gallons.Forget about having the truckstop do it. They charge $400 by the time your out of there. I shop around for oil on sale and buy filters from a truck supply place thats very reasonable.plan on a tube of grease too.

 

[roadrunner1]

According to Cat specs either 15w-40 or 10w-30 are acceptable grades in this engine.

My suggestion is to run the one year and sample, you will more than likely find that you can go several years between oil changes.

No need for a syn in this application. If it were me I would consider a 10w-30 as you have an HEUI system. These type of injection systems are well known to beat up oil and taking almost any 15w-40 and turning them into 30wt. in short order due to the system using motor oil as hydraulic fluid to operate the injectors.
10w-30 holds up much better and keeps the injectors happy.

 

[bullwinkle]

I do see that Valvoline PB Classic CI-4 is available in 10W30 now-if I didn't have a big stash already I'd stick a 55 gallon drum in the corner of the garage & (like the Frank's Red Hot commercial) put that (bleep) in everything!

 

[Gokhan]

You don't need 5W-40 in Seattle and 15W-40 is perfect for you. 15W-40 is a thicker oil than 5W-40 even when hot (HTHS viscosity ~ 4.3 cP vs. ~ 3.7 cP, respectively), and heavy-duty diesel engines, unlike gasoline engines, wear significantly less with thicker oil. This is because of soot in diesel oil, which requires the oil film as thick as possible. This is well-tested and proven. See Pages 14 - 16 of this presentation (PDF link). You will also save a lot of money with 15W-40, so it's a win - win situation. Fuel-economy benefits of 5W-40 vs. 15W-40 is only 0.5% (see the presentation linked above). This means unless you drive a lot, 5W-40 will be more costly for you thanks to more expensive oil changes and increased wear.

For the months, use manufacturer's recommendation but with modern diesel-engine oil, you can probably go 10,000 miles / 1 year, even with high-quality conventional 15W-40.

I would recommend Mobil Delvac 1300 Super 15W-40. It uses high-quality, Group II+ base stocks and has a high-quality additive package, including trinuclear moly. Cheaper 15W-40 oils use Group II base stocks.

 

[Ramblejam]

Originally Posted By: Gokhan
heavy-duty diesel engines, unlike gasoline engines, wear significantly less with thicker oil. This is because of soot in diesel oil, which requires the oil film as thick as possible. This is well-tested and proven.

 

[dnewton3]

Originally Posted By: roadrunner1
According to Cat specs either 15w-40 or 10w-30 are acceptable grades in this engine.

My suggestion is to run the one year and sample, you will more than likely find that you can go several years between oil changes.

No need for a syn in this application. If it were me I would consider a 10w-30 as you have an HEUI system. These type of injection systems are well known to beat up oil and taking almost any 15w-40 and turning them into 30wt. in short order due to the system using motor oil as hydraulic fluid to operate the injectors.
10w-30 holds up much better and keeps the injectors happy.


I whole-heartedly agree with this assessment, and I'll add this.

Your 2005 is long past any probably warranty coverage, so the "... or six months" OCI concern is a total waste. Given that you run 5k miles a year, it's very conceivable that you'd be able to run perhaps 2 years on one OCI, or maybe more. That would save you big money versus 4 OCIs in that same two years.

Yes, the cost of a UOA would be less than an OCI given your sump size. In your case it's cheaper to sample the oil and KNOW it's condition, than to assume it's bad and change it.

If you're not going to run greatly extended OCIs, then you'll not need synthetics.

You're new to the site; plenty to read and learn about.
To understand how to use UOAs, start here:
http://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/

As for a lube recommendation, I'll offer this advice ...
It's not going to matter what brand/grade you buy. As long as you stick to a normal OCI plan and operational use, you'll be fine. I would agree that a 10w-30 will often fare better in a HEUI system; it will shear much less. However, it's not a necessity by any means.


BTW ....

 

[roadrunner1]

t
Displacement . . . . . . . . . . . . . . . . . . . . . 8.82 L (538.2 cu in)
Rated Engine Speed. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2500
Bore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.0 mm (4.41 in)
Stroke . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149.0 mm (5.87 in)
Aspiration . . . . . . . . . . . . . . . . . . Turbocharged-Aftercooled
Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electronic
Cooling System . . . . . . . . . . . . . . . . . . . . . . Heat Exchanger
Weight, Net Dry (approx). . . . . . . . . . . . . . 946 kg (2,086 lb)
Refill Capacity
Cooling System . . . . . . . . . . . . . . . . . . 47.0 L (12.4 gal)
Lube Oil System . . . . . . . . . . . . . . . . . . 32.0 L (8.5 gal)
Oil Change Interval. . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 hr
Caterpillar® Diesel Engine Oil 10W30 or 15W40
Rotation (from flywheel end) . . . . . . . . . . Counterclockwise
Flywheel and flywheel housing . . . . . . . . . . . . . . SAE No. 1
Flywheel Teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Max. Exhaust Backpressure ... 10.0 kPa (40.2 in. water)
Fuel Consumption. . . . . . . . . . . . . . . . . 98.3 L/hr (26.0 g/hr)
Air Inlet System
Corrosion-resistant sea water aftercooler core, air
cleaner/fumes disposal system (closed)
Control System
Electronic governor, HEUI™ fuel system, A4 electronic
control module, engine-mounted 70-pin dedicated
customer connector, SAE J1939 data link
Cooling System
Thermostat and housing, belt-driven centrifugal jacket
water pump, gear-driven auxiliary sea water pump,
expansion tank, engine-mounted heat exchanger,
removal tube bundle (for sea water), engine oil cooler,
auxiliary sea water lines, transmission oil cooler
Exhaust System
Watercooled exhaust manifold and wastegated
turbocharger
Flywheel and Flywheel Housings
SAE No. 1 flywheel (113 teeth), SAE No. 1 flywheel
housing
Fuel System
Fuel filter (RH or LH service), fuel transfer pump, fuel
priming pump
Lube System
Crankcase breather, oil filter (front center service), oil
filler (RH or LH service), oil level gauge (RH or LH
service), oil pan, oil pan drain (RH or LH service),
lubricating oil, gear-driven engine oil pump
Mounting System
Front support (adjustable height)
Protection System
Electronic overspeed shutoff
General
Torsional vibration damper and guard, lifting eyes,
literature, variable engine wiring, RH or LH service
options
ISO Certification
Factory-designed systems built at Caterpillar
ISO 9001:2000 certified facilities
C9 ACERT®
MARINE PROPULSION

I pulled this from a marine info page from Cat, hence the 10w-30 reccomendation.
510 mhp

 

[Ramblejam]

Originally Posted By: roadrunner1
I pulled this from a marine info page from Cat, hence the 10w-30 reccomendation.


Page 8 for on-highway recommendations: http://parts.cat.com/cda/files/3244668/7/SEBU6385-08 secure.pdf

Rotella T3 10w-30 is available from your local Wal-Mart (No.: 004214359).

 

[Gokhan]

Originally Posted By: Ramblejam
http://parts.cat.com/cda/files/3244668/7/SEBU6385-08 secure.pdf

Thanks! This is a great reference -- I saved it.

The following single sentence that is repeated many, many times on Pages 14 - 16 summarizes what oil viscosity you should use in a heavy-duty diesel engine:

"Generally, use the highest oil viscosity that is allowed for the ambient temperature when you start the engine."

This is exactly what I said in my detailed explanation above.

Therefore, 15W-40, not 5W-40 or 10W-30, is the the correct heavy-duty-diesel-engine oil viscosity for Seattle. 5W-40 or 10W-30 will both result in significantly increased wear over 15W-40 in a heavy-duty diesel engine due to their smaller HTHS viscosity and they should only be used in very cold temperatures in heavy-duty diesel engines. Smaller diesel engines or newer heavy-duty-diesel-engine technologies may be exceptions.

Note that, in contrast, for gasoline engines, the rule of thumb is to use the lowest viscosity allowed. This is because there is not as much trade-off between fuel economy and engine wear for a gasoline engine, as they are much more tolerant of thinner oil film, thanks to lack of abrasive soot particles that grind against metal within the oil film and lower torque at lower RPM, which increases the minimum oil-film thickness for a given viscosity in comparison to diesel engines.

 

[Doug Hillary]

Hi,
Gokhan - You said this:

"5W-40 or 10W-30 will both result in significantly increased wear over 15W-40 in a heavy-duty diesel engine due to their smaller HTHS viscosity and they should only be used in very cold temperatures in heavy-duty diesel engines."

Generalised statements are open for serious dispute. I've used 5W-40 in my heavy high speed diesel 12.7ltr engines over millions of kms with excellent results. My engines operated in temperatures from below freezing to 42C. Tear down inspections confirmed this. Typically the HTHS viscosity of a 5W-40 synthetic is similar to 15W-40 mineral lubricant

 

[Ramblejam]

Originally Posted By: Gokhan
5W-40 or 10W-30 will both result in significantly increased wear over 15W-40 in a heavy-duty diesel engine due to their smaller HTHS viscosity and they should only be used in very cold temperatures in heavy-duty diesel engines.


That's simply untrue, Gokhan. See pages 12-22 for analysis results:
http://www.parmanenergy.com/sites/defaul...0-%20021613.pdf

As well:
http://www.kenworth.com/news/news-releases/2013/march/chevron-oil.aspx
"standard factory fill for new Kenworth Class 8 diesel trucks"

 

[roadrunner1]

I have yet to see any evidence of increased wear between 10w-30/15w-40.
In my own experience with UOA's I have seen LESS wear using 10w-30.

The engine manufacturer offers both grades as acceptable, so its not like we are venturing off into unknown territory with a lighter grade. The myth of needing a 40wt. in medium/heavy diesel applications is eroding fast.

For many years these engines ran for thousands of hours on straight 30wt.

 

[Gokhan]

Originally Posted By: Doug Hillary
Hi,
Gokhan - You said this:

"5W-40 or 10W-30 will both result in significantly increased wear over 15W-40 in a heavy-duty diesel engine due to their smaller HTHS viscosity and they should only be used in very cold temperatures in heavy-duty diesel engines."

Generalised statements are open for serious dispute. I've used 5W-40 in my heavy high speed diesel 12.7ltr engines over millions of kms with excellent results. My engines operated in temperatures from below freezing to 42C. Tear down inspections confirmed this. Typically the HTHS viscosity of a 5W-40 synthetic is similar to 15W-40 mineral lubricant

Thank you Doug.

The minimum HTHS viscosity SAE spec for 5W-40 is 3.5 cP. The minimum SAE spec for 15W-40 is 3.7 cP. Typically 15W-40 will have an HTHS viscosity of about 4.3 cP and 5W-40 will be have an HTHS viscosity of about 3.7 cP. This is a substantial difference. If they both had the same HTHS viscosity, there would be no fuel-economy benefit of using 5W-40 because the fuel economy is determined by the HTHS viscosity (= hydrodynamic friction).

 

[Gokhan]

Originally Posted By: Ramblejam
Originally Posted By: Gokhan
5W-40 or 10W-30 will both result in significantly increased wear over 15W-40 in a heavy-duty diesel engine due to their smaller HTHS viscosity and they should only be used in very cold temperatures in heavy-duty diesel engines.

That's simply untrue, Gokhan. See pages 12-22 for analysis results:
http://www.parmanenergy.com/sites/defaul...0-%20021613.pdf

As well:
http://www.kenworth.com/news/news-releases/2013/march/chevron-oil.aspx
"standard factory fill for new Kenworth Class 8 diesel trucks"

Thank you for the references.

The first reference is a marketing brochure and they cleverly omit any wear comparison against 15W-40.

The second reference clearly states that 10W-30 is for the newer, 2013+ engines. These newer engines are designed more tolerant to smaller oil-film thickness of 10W-30. It's the same as newer gasoline engines being built tolerant to smaller oil-film thickness, such as 0W-16 viscosity coming soon for 2015+ gasoline engines.

An impartial wear comparison is in the Chevron/Oronite presentation I linked above, showing that there is even significant wear increase when going down in viscosity from 15W-30 to 10W-30.