Changing oil in Cummins Onan generator

[Wayne]

Our trailer has a 6.5KW Cummins Onan model number 6.5HGJAE propane powered generator. We were supposed to get the green RV generator, but production is about 50 weeks out on the RV generators, so we ended up with a 6.5KW industrial propane generator instead. I have no idea what the functional difference is between RV and industrial, but I will say that the industrial appears to be extremely well built. I expected to see a Briggs, or similar, V-twin, but it's actually an Onan HD V-twin.

I was told to change the oil at 5 hours and I figured 3.7 was close enough and since we're going out on a trip, I figured I would change it now.

The oil filter is a bit hard to find, because it's a HD oil filter, which I believe has a thicker can and higher burst pressure, it sure is heavy and kind of reminds me of the Allison spin on transmission filter. The only brand I could find local was a Car Quest 84389 and I will post the Fram equivalents below.

The generator is mounted underneath the floor and just behind the rear axle. You can sit on the ground and have very easy access to everything needed to change the oil. The filter is accessed from the underside of the generator and there is no oil plug, instead there is a petcock and a drain hose. You can't get much simpler than that. The filler mouth is large and an oil bottle spout fits perfectly into the opening.

The oil capacity is 2 quarts and the manual requires 15w-40 down to +5°F. I used High Performance Lubricants 15w-40.

Fram cross reference

• Wayne
• Jul 24, 2021

Generator

• Wayne
• Jul 24, 2021

service door removed

• Wayne
• Jul 24, 2021

Bottom side of generator

• Wayne
• Jul 24, 2021

Dipstick, filler, and drain petcock

• Wayne
• Jul 24, 2021

HPL

• Wayne
• Jul 24, 2021

HPL going in

• Wayne
• Jul 24, 2021

 

[Azjeff]

Wow, should be no worries running whatever you want. I never knew they were open to the road, is the case sealed up so it doesn't get covered in road grime inside? Do you have solar?

 

[Wayne]

I never knew they were open to the road

Many 5th wheel manufacturers put gen sets in the basement, which takes up most of the room in the basement. New Horizons, a few years ago, started putting them behind the back axle, which obviously takes up zero room in the basement.

I never knew they were open to the road, is the case sealed up so it doesn't get covered in road grime inside?

The case is mostly sealed, except for air intakes, but it will get some road grime if we travel in the rain. It's a trade-off between more room in the basement and some road grime. I'll keep is as clean as possible, because I'm a BITOGer

Do you have solar?

We don't boondock much, so we didn't opt for solar. Plus, New Horizons are not solar experts, so if you are going to get solar, it's best to have it done with a company that specializes in solar. We did have it prewired for solar, which was a cost of $300, a bargain compared to the cost of trying to run wires after the build. If we ever decide to install solar, then we are prepared, however it's not likely.

 

[gobi]

Many 5th wheel manufacturers put gen sets in the basement, which takes up most of the room in the basement. New Horizons, a few years ago, started putting them behind the back axle, which obviously takes up zero room in the basement.


The case is mostly sealed, except for air intakes, but it will get some road grime if we travel in the rain. It's a trade-off between more room in the basement and some road grime. I'll keep is as clean as possible, because I'm a BITOGer


We don't boondock much, so we didn't opt for solar. Plus, New Horizons are not solar experts, so if you are going to get solar, it's best to have it done with a company that specializes in solar. We did have it prewired for solar, which was a cost of $300, a bargain compared to the cost of trying to run wires after the build. If we ever decide to install solar, then we are prepared, however it's not likely.

what gauge wire did they put in for solar?

My neighbor just bought an off road aussie trailer and a dmax, he is taking his trailer to utah to get the solar done with lithium battery.

 

[Wayne]

what gauge wire did they put in for solar?

I don't know, but I was told it's the standard harness they use for all their solar installs.

 

[spasm3]

Nice! thanks for the pics. I'd wax or use something on that gen cover so you can spay it off clean for service, it will get road dirt.

I'm curious about HPL oil, is it a high TBN oil?

 

[Wayne]

I'd wax or use something on that gen cover so you can spay it off clean for service, it will get road dirt.

You are correct. This is what it looks like after 1,000 miles of road grime

I'm curious about HPL oil, is it a high TBN oil?

Yes, the HD oil has a TBN of 15. My Durango will have 18 months and 21,000 miles on HPL HD 5w-20 in about a week. I will sample and send it in