11.5kW diesel generator - oil recommendation?

[3930dave]

The "no fully synthetic" actually came from a Cummins service rep, which surprised me since the manual only specified viscosity and API rating. But as you said maybe synthetics weren't much of a consideration at the time it was manufactured.


Good question. I don't have a way of externally warming, at the moment.
It has never started well below freezing, no. I've only addressed it through a steeper kero:diesel mix (was told by the guy who serviced for me that we could go up to full kero, but have never been empty when it's time for the winter kero fill so we normally end up about 50:50). It's not uncommon to have gelling issues, or what I assumed were gelling issues. Generator powering the cabin, then it shuts down on a real cold night. I'd normally add Diesel 911, change fuel filters, and hope for the best. After looking through the manual, began to think maybe going down to 5w30 would help at least with the slow cold starts, since I've never put that in and the manual recommended it for the sub zero temps. (That thinking may be off base, I'm fairly clueless).

Maybe at 7500 hrs I should spend more time thinking about how to save for when this machine kicks the bucket

On the rating story, C_ diesel-oil is fairly straight-forward (vs. the newer classes), and are backwards-compatible.

Oil Categories

On air-cooled applications, there can be a case for Conventional, but I'm guessing that your Onan is water-cooled (?).

Wide-range synth (like T6) are OK by me, but for specialty options, I often end up checking Amsoil.... may be a dealer near you, or they do ship.

Sounds like your biggest problem is staying-Running @ ColdNight.... I'd be tempted to look at something like a fuel-bowl warmer, and see if that makes a difference (infra-red heat lamp, if nothing else, if you can safely position and secure one.... or even just a regular incandescent 100w PAR30 bulb - making up a small cage around it with rodent-grid wire (Home Depot, etc) is one way to prevent direct (fire) contact with the bulb surface).

I regularly treat diesel with Stanadyne Performance..... that, or equivalent, can help improve Cetane, and manage water-issues.

Rgds, D.

 

[LouNY]

I'd simply switch the oil to a quality synthetic 5W-40 for year round use.
As far as it gelling after you get it started, a shroud with a simple thermostatic control to keep it warmer in cold weather would stop that or add some heat pads to the fuel filters.

 

[Chilliwack Murray]

Outside of break-in issues, the main issue with the early synthetics was seal and gasket leaks. The materials used at the time would not contain synthetic oil and some soft parts were damaged by some of the synthetic oils. You should have no issue using any of the mainstream synthetic blends available today but that unit won't really benefit from the top of the line synthetics vs a blend for half the money, just stay within the viscosity range specified. That unit has a Lister-Petter engine and you will find a lot more info on the Listerengine forum since that's their 'thing'. I would go with the Lister Petter specs rather than the Cummins owners manual as Cummins documentation will lean toward what Cummins has available as long as it will work, but not necessarily the best choice.

If I recall correctly, the glow plugs weren't connected on these gensets originally as they were built for emergency standby and were intended to have a block heater to maintain the engine around 130F. (no time for glow plugs when you have to be supplying power in 15 seconds). Check if there is a wire on the glow plugs, and if it actually goes anywhere. If not, hook them up to a momentary pushbutton switch rated for the current and that will help starting immensely, and as a bonus you have brand new glow plugs.

Those were fairly reliable standby units but prone to leaks and carbon buildup that could damage pistons and injectors. The few I saw with high hours needed regular valve adjustments. At 7500 hours you are probably 3/4 through its life. If you can find a Kubota powered unit to replace it, they will run 30,000 hours with just regular maintenance and I've seen them run well over 50,000 hours with no major repairs.

 

[Mike1955]

ADK your original post was about oil, I think. My preferred brand although I don’t always have it is Amsoil. I think it would serve you well to. Viscosity is something you may just need to change for. I enjoy the extended change intervals too.

 

[big bubba]

welcome to forum. have you inquired directly w/Onan as to their current recommendations? regards