RV service, how often.

It sounds like you are just talking about an oil change, which is usually done once per year unless you are putting on a lot of miles. But there is a lot more maintenance that should be done. You need to get the maintenance schedule for your engine and chassis and make sure all the periodic maintenance has been done.

My routine is:

Oil and lube every two years
Tranny every 4 years (Transynd)
Coolant (ELC) every 4 years
Both Hydraulic Tanks every 4 years.

So basically I'm doing something every year along with a fluid analysis.

Engine is a 505 Cat C-12 with 36 qts of oil.
Allison 4000 shallow sump

Sounds like you are talking about an oil change--servicing a motor home involves more than changing the oil. You have oil, fuel filters, chassis and drive train lubrication, air filter, air dryer, transmission service, hydraulic fluid service, and others. They all have different intervals.

You didn't say anything about what has been done with the engine since last December. Has the coach just been sitting or have you exercised the engine during the last 8 months or so?
If it has been sitting this whole time, it may be a good idea to check to see if any moisture has accumulated in the crankcase that would necessitate an oil change.
If it has been used/exercised during those 8 months then you should be fine for a 4000 mile trip.

On a C7 Cat it depends on the size of the oil pan. The 19 quart pan requires more frequent oil changes. You instructions should tell you.

oil test
My 1972 Prevost would allow 100,000 miles between oil changes if the test confirm quality.

when the oil analysis says to......

Mandalay Parr wrote:
Once a year or 11,000 miles per CAT for mine.

+1

Once a year or 11,000 miles per CAT for mine.

You've been putting about 3,500 miles a year on your MH. Once a year is plenty. If you were putting a lot more miles on it, do it at 10,000 miles. If there's a Speedco near a grocery store, let the DW do the grocery shopping while you get an oil and fuel filter change. I prefer to take my own filters as they don't always have exactly what I prefer, but I always have at least two spare sets with me. They can also do the generator.

Bill