Annual Oil Change?

[akadeadeye]

Due to a plethora of reasons, including rotator cuff surgery, healing, recovery, etc. our coach will have traveled less than 1,000 miles by the end of this year. Bummer. I know I have been told that the oil should be changed annually, regardless of usage. First, is this really necessary, and if so, why? I don't change the oil myself so this ends up being an expense that is more noticeable when there is almost no road time to show for it. We have a Cummins 400 ISL and I have had the oil changed annually since we got the coach, as directed. Is it ever acceptable to skip a year if there is almost no usage?

Don

[wolfe10]

Don,

Best reason with a 2009 coach is to have no question when it comes to the engine warranty.

Second reason is that moisture does form in the crankcase, particularly in a fairly humid area like S Texas.

[akadeadeye]

Those are excellent reasons Brett. Does oil acidify within a year or so or is it the moisture problem?

Don

[wolfe10]

Don,

The two are related, as moisture plays an integral role in the formation of acids in oil. This is less of a problem today than in the past, as sulfur plus water produced sulfuric acid and was one of the more frequently produced acids. The ULSD fuel has reduced the amount of sulfur available to form acid.

[five]

As noted above, compare the cost of an oil change versus the cost of serious engine problem if the warranty is voided.

[Briarhopper]

This may not be applicable to an engine under warranty. I plan to use oil analysis to detemine when to change the oil. When we bought the coach we have, I wanted an idea better than a guess as to the engine condition, so I sampled the oil. I figure why not continue the practice.

This is the first engine I have used oil analysis on, so it's a trial for me. Don't know why it wouldn't work for checking oil that only had 1,000 miles on it other than the warranty issue. Might be worth a call to Cummins and see what they say. A lab report might be as good as an oil change service record. Might be other service factors to consider though.

BH

[danddferr]

An oil change is a cheap preventative step to take to safe guard your engine. The little you save by not doing it is small compared to what you are risking.

Dan

[Briarhopper]

Had an interesting and educational conversation with the lab after sampling engine oil for the second time in the Cummins. Happy to report no big flags.

This last sample was taken at 5,000 miles and 5 months since the previous sample. Most of the mileage has been in longer runs over 2 to 7 day periods and we have sit parked for a majority of days in the 5 month period (21 total travel days and the rest parked).

Two little bitty flags worth noting and very pertinent to the topic of oil change interval. The base number was down but still above acceptable level and adequate to combat acidity. Iron was up slightly, but still below acceptable level.

Both the dropping base number and rising iron can be contriubuted to engine conditions while sitting; base number dropping due to acid formation as Brett mentioned above and the iron rising due to rust formation internally in the engine.

Theorectically, going forward the base number will be improved each time I add a little oil, but at some point will be overcome by the formation of acid and will likely be the big flag that indicates time to change the oil.

The other likely condition that will call for an oil change will be overall contamination, which if understand correctly, will happen with operation rather than no operation.

We'll sample again at 10,000 miles or 12 months.

BH

[vsheetz]

I have multiple low usage vechiles - old pickup truck, Jeep, and the motorhome - I change oil annually in my birthday month.