Oil for water-cooled, standby generator?

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MRKing

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My search for info on this topic has been mostly fruitless, and I am hoping somebody here can enlighten me.

I bought a house with an 11 year old, 25kW, water-cooled, natural gas, Generac generator. The manual for the machine says oil should be 15w40 with API CC, SD, SD, SF. Of course, those are old, obsolete classifications.

We have few power interruptions here, so most often the machine runs a few minutes each week on an automatic maintenance cycle. (It ran more than that only once in the last 8 months, running for a few hours when a car hit a nearby utility pole). Of course, when a hurricane comes, it will likely be asked to run continuously for several days.

I did find in the auto-related forum info on oils for smaller, air-cooled generators, but many of the reasons provided for the oils recommended there don't seem to apply to this situation. Can somebody recommend what oils I should consider for this application. Any information on why those particular oils are recommended would go a long way towards taking me from ignorant to informed, and would be hugely appreciated!

Thank you,

Mike
Pensacola, Florida
 
Run a 15w40 gas/diesel oil. I think your generator is more than 11 years old. I think they implemented sm oils in 2004, from the old sj spec.
 
Run a good 15w40 and that is plentiful. Going to supply half the neighborhood with that overkill of 25kw?:) Got a friend into a 10 kw several years ago in Melbourne and has only used it a handful of times and says that it kinda creeps her out when she looks out the window and the area is all black except for her place.
Original owner probably found a good deal hence the oversize. My friend had the deal literally fall off the truck
 
In Florida, any plain ol' 15w40 HDEO will be just fine. These engines don't need exotic oils.

If you want to splurge, get Rotella T6 5W-40... but it's not necessary.
 
Thicker oil was more popular back in the day then it is now, but the trend is moving back towards favoring thicker oil to answer your question. At least for small engines
 
Originally Posted By: bioburner
Run a good 15w40 and that is plentiful. Going to supply half the neighborhood with that overkill of 25kw?:) Got a friend into a 10 kw several years ago in Melbourne and has only used it a handful of times and says that it kinda creeps her out when she looks out the window and the area is all black except for her place.
Original owner probably found a good deal hence the oversize. My friend had the deal literally fall off the truck


Why do you say it's overkill? Houses in my area are two stories with an upstairs and downstairs air conditioner. I lived in a one story has and had the biggest air conditioner you could put in it without stepping up to a commercial series. I forgot how many tons it was.
 
I was involved in standby generators for about 10 years. Use a diesel rated 15w40. For a maintenance schedule run the engine for a very short time and put a load on it just to test it. If you're not going to run up to normal operating temperatures then run it as short of a time as possible and still put at least a nominal load on the system just long enough to check. The shorter the run the less gunk you will generate that will sit in the oil.

At the end of one year get a used oil analysis and then determine the OCI. At that time check the coolant to determine a service schedule and don't forget the air cleaner and the general cleanliness of the engine and enclosure including the electrical connections and battery. Use Pledge Furniture Polish (not a joke) to clean the battery.
 
Deere Plus 50 II CJ-4 15w40, its specced for your application (natural gas) and designed for situations for long non-use. Its competitively priced with other HDEO's.

I would NOT use a 5w-40 in your application as its only advantage being cold-starts vs a 15w40, and in FL you will never need the 5w.
 
Thanks for the replies, everyone. I wasn't at all certain if the diesel oil was appropriate or if perhaps it had additives (or lack thereof) which would be unsuitable for a natural gas generator.

As to the generator's age, the prior owner of the home left me all their paperwork (semi-annual service tickets as well as the original receipts and install notes) so I know when it was installed, and that was 11 years ago. Perhaps he also got a "deal" on an older machine somebody had in inventory, or perhaps he was simply taken advantage of - I have no way to know. I would add that as to the size, the generator powers two buildings (there is a shop which was converted into a guest house), each with its own heat-pump AC (a 4-ton and a 5-ton). Also online are a well pump and a sewer lift-station pump. All in all, that's one heck of a load.

After reading what everyone's said, it sounds like the majority opinion is that pretty much any HDEO synthetic 15w40 would be fine (with two posters specifically recommending diesel and one for Deere Plus). Having owned a Deere tractor I know those guys are REALLY fond of anything with their name on it and price it accordingly.

Oh - and OneEyeJack said "At the end of one year get a used oil analysis and then determine the OCI." Hmmm... I guess I need to do a bit more reading so I know what those mean, but even now am guessing used oil analysis is some specific oil analysis, and OCI is Oil Change Interval. (Told you I was ignorant; but I am educable and can read and learn pretty well.)
 
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SilverFusion2010 - Thought I should reply to your specific recommendation . . . I use Amsoil products in my car and in my Honda VTX1800 V-Twin, but those are two VERY different oils and I (still) have no idea if either of them would be appropriate for the generator I now own, or if one might be better than the other. Heck - I am still trying to learn which oils would be classified as HDEO vs those which would be classified as ordinary automotive oils. The depth of my ignorance on lubricants shouldn't be underestimated!
MK
 
Originally Posted By: MRKing
SilverFusion2010 - Thought I should reply to your specific recommendation . . . I use Amsoil products in my car and in my Honda VTX1800 V-Twin, but those are two VERY different oils and I (still) have no idea if either of them would be appropriate for the generator I now own, or if one might be better than the other. Heck - I am still trying to learn which oils would be classified as HDEO vs those which would be classified as ordinary automotive oils. The depth of my ignorance on lubricants shouldn't be underestimated!
MK
If you want to know about HDEO oils, they usually have the API ratings like CK-4, older ones are CJ-4, CI-4 and so on. I don't know about Florida, but around here, 15w40 in full synthetic is not around. Full synthetic HDEO is usually 5w40 and if you want to source it at a good price, that would be the one I would go after. For Amsoil, this is what you would look at: https://www.amsoil.com/shop/by-product/motor-oil/diesel/
 
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Originally Posted By: MRKing
SilverFusion2010 - Thought I should reply to your specific recommendation . . . I use Amsoil products in my car and in my Honda VTX1800 V-Twin, but those are two VERY different oils and I (still) have no idea if either of them would be appropriate for the generator I now own, or if one might be better than the other. Heck - I am still trying to learn which oils would be classified as HDEO vs those which would be classified as ordinary automotive oils. The depth of my ignorance on lubricants shouldn't be underestimated!
MK


I meant a HDEO

Rotella t4 would work well. Cheap, available at Walmart. Keep the super expensive stuff for your car and bike. If you look at the owners manual for your generator you should find an oil recommendation and a service interval in hours. Follow that and you'll be fine. Make sure you exercise the generator with a load every couple months.
 
SilverFusion2010 - Thanks for the additional clarity, as I know what I need to now. To clarify, the manual recommendations were the reason I had difficulty to begin with, as that the manual says oil should be 15w40 with API CC, SD, SD, SF. Those are old, obsolete classifications, so you can't find them on oil any more.

Ultimately, I decided to let the local certified dealer do my initial service on the machine (which happened yesterday) so that I could feel comfortable I knew everything they did and could determine whether I had the skill set and tools to do it myself. The tech used in Mobil 1. Including replacing the battery ($100) the service call cost me just over $400. Yeah - I think I can do it myself going forward.
mk
 
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