Standby Generator Oil Recommendation

[brewerbob]

I have just purchased a Generac Guardian 13kw standby generator which will run on propane. It will sit in its' own enclosure outside in our winter weather which can get down to -30 degrees, and summer which can be 100 degrees. The recommended oil change interval is 2 years after an initial 6 month change. The engine is twin cylinder 996 cc air cooled. They recommend synthetic 5w30 below -10 degrees and 10w30 above. I'm thinking that after the initial break in I'll use Rotella 5w40 synthetic in all cases. Let me know your thoughts.
Bob

 

[pickled]

I'd use Amsoil ASE Formula 4 Stroke 10W30 for a 2 year OCI in those conditions. It's specifically made for protecting air cooled engines and I posted a UOA on here a couple of months ago from some abused mowing equipment that was out of sight. It has a pour point of about -40F to boot. You don't need a 40 grade oil in that application, but if you can get Rotella 5W40 locally, and cheap, I don't believe it would hurt anything other than a slight loss in hours/gallon of fuel.

 

[Brett Miller]

I'll second the ASE.

 

[Best F100]

Hey brewerbob,
I have owned that same generator for almost the past 5 years. (however, mine runs on natural gas). They are loud, relatively cheap for a standby generator, and effective. We seem to loose power 2 or 3 times/year. Maybe we don't pay enough taxes in this part of Michigan, or maybe we are late paying our utility bills, I don't know. This is what works, and does not work so well:

1) I have no experience on Amsoil ASE. So I can't comment.
2) Castrol 0W30 (made in Germany variety) seemed to work the
best. Very little consumption power outages (15 hours).
Slightly less valve "clatter" noise according to my ears.
3) Straight 30 wt. Havoline worked well in a 30 hour 90F outage.
Some was consumed but the generator never shut
off due to low oil level. It was the first one I used after
initial break in. (I didn't know the outage would last this
long, otherwise I would have used a synthetic oil). Oil did
look real "beat up" and black as tar.
4) Mobil 1 0W30. I consumed almost 1/2 quart of the 1 3/4 qt.
capacity in about a 15 or 16 hour outage in 10F temperatures.
My generator did not quit, but I have heard of others, when their generator quit, having to refill the oil level using Mobil 1 5W30 after the oil level
got too low (it is a thin 30wt oil) in their air cooled
generators.

I am partial to Castrol 0W30 - if you can get it, for year round usage. I noticed you are in the state of Washington. If you can go across the border in Canada and buy Esso XD3-0W30, that would be a good bet. It, like the Castrol 0W30 are almost 40wt oils. I have some of that laying in wait, for the next big outage - whenever that is. I see no reason, Rotella 5W40 should not work effectivly. I am sure someone else who uses it will chime in.

I change my oil for summer & winter every 6 months (unless I loose power for extended periods in between). Also, the big tip, that I have picked up: The oversized Toyota Corolla oil filter, Purolator Premium Plus # L14477 is a perfect fit for this generator. With it, you can pour the full 2 qts, instead of 1 3/4 qts.

 

[JoggingGuy]

I have a Generac Ultra Source portable generator with the same engine. I did the break-in with Havoline 10W30 and switched to PP 10W30 Full Synthetic year-round after that. We don't really have an issue with cold temps in Houston, but the PP is working well in the 100F heat.

 

[benjamming]

I have the 15kW also on propane. I changed the green factory fill after 8 hours. My results are in the UOA section of this board. I filled up with the AMSOIL ASE as well. I don't have a UOA of this yet to provide any substantial feedback.

Best F100,

Have you checked valve clearances? How were they?

 

[dnewton3]

I think you'll do fine with about any 10w-30 synthetic PCMO you choose. Your average temps are 81 deg F for a high, and +15 deg F for a low. Sure, you might get a tad bit hotter or colder on occasion, but not THAT much different. I really rather doubt you'll get below -10 deg F to warrant the 5w-30 grade.

I would say that a 5w-40 is not a bad choice, but it may not be the best choice. That extra little bit of power needed to pump a more viscus fluid might draw down a bit of the power you are seeking for powering equipment. But that's a very small issue in reality. Overall I doubt you could tell the difference, but in theroy, the issue does exist.

The oil grade you choose isn't going to effect the starting of your unit near as much as the condition of the starting battery. Make sure you keep your battery in good shape! Consider a gel-cell or AGM battery so that unintended neglect can be tolerated a bit more.

Another thing to note is that while propane runs a bit dirtier than natural gas as far as combustion byproducts, they both pale in comparison to the aftermath of junk that gasoline produces. So in that regard, the detergent/dispersant package of about any oil would suffice. There are oils that are specifically made for use with natural gas and propane powered equipemnt. However, I don't think this scenario of stand-by limited use warrants such consideration. The exposure factor just isn't that great. If it were, Generac and others would specify as such, but they don't.

You'll be changing oil due to time (2 years), rather than exposure (mileage), right? My suggestion is to pick any group III that you can find on sale in 10w-30. You could choose a more expensive option, but since you're not going to be extending OCI's with use of UOA's, what's the point? While some here would debate the merits of group III vs. group IV, I just can't see the value in such nit-picking for a limited use item.