Our particular 2007 Airstream Interstate has an unusually tight lay-out for two reasons. Number one, it's not built on an extended ("EXT") Sprinter model, so it's shorter than many Class Bs, including most newer Interstates. And number two, it has an under-mounted spare tire that impinges on the generator space. For these two reasons, I thought I'd throw out some oil change tips, while not repeating the entire set of details that have been published by others. You might want to see Tito's YouTube as a general primer for this task before continuing to read the account given below.
Note that our unit is a 10-year-old Onan 2500 propane (not gasoline) generator. Apparently the modern-day 2500 is either gasoline or propane-powered, but ours only accepts propane.
|It's also very dirty in this pic. No sense washing it until after the oil change is done.|
|These are the Interstate-specific ramps I built using wood I that picked from trash piles as our subdivision perimeter fence was being replaced by a contractor. Blog post with instructions here.|
|Just as I got very comfortable working underneath our Interstate, so too did our dog.|
The oil drain plug is easy to locate (see Tito's video linked above). There's no way around the need for a 9/16ths socket for this job, as Tito says. No other tool will substitute because the plug is recessed.
|I've got the socket around the plug, but here's an important point below.|
|It's now loose enough so that oil begins to leak past the threads.|
|Bolt removed, let drain 5 or 10 minutes into the oil pan below. It will take a while.|
|Looks good to me.|
Now here comes the tricky part.
|This (yellow funnel) is not necessarily the best way to get new oil back into the genset.|
They do make a small pump (something akin to a jumbo hypodermic needle with a flexible tip) that can be used for this sort of thing - I didn't know that until after we finished the job. A simpler method might be to pour successive fractions of the quart of oil into a smaller, shorter container, say about a cup or two in size, and then lift that up to the funnel successively until the entire quart is transferred. It's bound to be a bit messy, so make sure you have a tarp under your vehicle.
And speaking of new oil, what kind should be used?
Our Onan users manual says very little about the grade, other than it should be SAE 30. But we decided to use this.
|Image from Onan's (Cummins') generator handbook (PDF link).|
Speaking of filling, I also read (as in, RTFM) that the dipstick should not be screwed in when reading the oil level.
|The dipstick is also the reservoir cap. Sorry for the blurry pic. It's challenging to take pics one-handed under the chassis.|
After you get the dipstick replaced, it's time to clean the outside of the generator thoroughly. That way if oil starts coming out of any given orifice, you'll be able to see it. Go back six or eight hours later and examine the drain plug for evidence of slow leaks.
|See, now the underside is shiny because I cleaned off all the dirt. That's the drain plug in the lower center-ish part of the photo. No drips are visible.|
|That way you can spend it on some other aspect of your Interstate, hahahah.|