Air Cooled Standby Generac Generator oil questions

[lgndryhr]

I am coming up on due maintenance for our house generator. It is a 20kW air cooled standby Generac with an Eaton engine and uses natural gas. My late father-in-law always paid local electrician to maintenance. I was looking over the Generac literature. Manual states 5w30 with a preference for synthetic. I now see Generac recommending 5w20 for their generators over 5w30. I am going to stick with 5w30 unless there is a better recommendation or reason to go with 5w20.

Generac page about oil: https://support.generac.com/s/article/What-Type-of-Oil-Should-I-Use-in-My-Home-Backup-Generator

I imagine the Generac branded oil in the maintenance kits is overpriced vs something I can buy at the store. I have some extra AMSOIL Signature Series 5w30 and extra Mobil 1 Full Synthetic 0w40. Could I use either of those or would I better off using small engine rated oil?

Also any input on oil filters?
I looked up the Generac filter part and found this site:
https://www.finditparts.com/products/2523626/wix-filters-57145

 

[meep]

I can’t possibly imagine using a 20w oil in an air cooled engine. Perhaps they are concerned with winter starting? Can a small block heater be affixed to one of these? It wouldn’t take much. Or make sure the battery is replaced preemptively.

 

[loneryder]

I use Mobil 1 or Castrol EDGE 0w40. Easy cranking in cold winter and god protection in hot weather.

 

[Trashman]

The Wix 57145 that you listed is a very popular size for Toyota engines. Fram 4386/4967, Purolator 14477/14476. If you look for filters for a 2002 Camry with the 2.4L 4 cylinder, those will cross to your Wix 57145.

 

[fozzdesy2001]

I use Mobil 1 or Castrol EDGE 0w40. Easy cranking in cold winter and god protection in hot weather.

These are really good

 

[SwampDweller]

For 10 years now I have been running 15/40 Mobil Delvac. First in a 20KW Generac 999cc for 6 years. Sold that home and now have a new home with a 17KW Cummings with the same 999cc V twin for 4 years.

Down here outside New Orleans, we get a fair amount of outages in a years time. Most are short lived, measured in hours as opposed to days. I change the oil/filter once a year regardless of hours. 2 quarts and a filter, very quick service.

If you live in Mississippi, I might do the same.

 

[oil pan 4]

It's got an electric start I'm sure 5w-30 amsoil will be quite sufficient.

 

[kschachn]

Here in the north I use an oil with an approval such as VW 504 00 with the resultant minimum HT/HS. However, if I lived in Mississippi I'd probably look into using a -50 grade. Film thickness is your friend especially in a piece of mission critical machinery.

@Cujet has some relevant posts on this subject. He's made a good argument for an HT/HS of 3.8 or above. There is zero technical reason to use a -20 grade in that engine.

 

[Tom NJ]

Generac's brand of 5W-20 synthetic oil states it is a low ash (low SAP) oil designed for gaseous engines, apparently for deposit control (Generac 5W-20 label). A VOA bears this out showing relatively low CA and ZDDP levels (Generac 5W-20). Their literature only states oil recommendations, not requirements, so there is flexibility in viscosity. I will be using Mobil 1 ESP 5W-30 (lower SAP) in my new Generac 26kW generator as I prefer a higher HTHS viscosity for this air cooled engine.

My post in a previous thread repeated below:

I just had a Generac standby 26kW whole house propane generator installed last week. The owner's manual sets no requirements for the oil! It just says that "All Generac oil kits meet minimum API Service Class SJ, SL or better" and "It is recommended to use Generac's proprietary 5W-20 gaseous engine oil for continuous use".

Their website, however, recommends "Generac 5W-20 full synthetic oil for all home standby generators, no matter the temperature", but also allows a straight 30, a 10W-30, and a synthetic 5W-30 for specific temperature ranges. All recommendations, no requirements.

Generac Oil Recommendations

 

[wavinwayne]

When I change the oil in my 22kw Generac, I'm using Mobil 1 ESP 5w30 because that's what I'm running in everything now.

 

[Cujet]

Here in the north I use an oil with an approval such as VW 504 00 with the resultant minimum HT/HS. However, if I lived in Mississippi I'd probably look into using a -50 grade. Film thickness is your friend especially in a piece of mission critical machinery.

@Cujet has some relevant posts on this subject. He's made a good argument for an HT/HS of 3.8 or above. There is zero technical reason to use a -20 grade in that engine.

There is no warm weather situation where I'd run an air cooled generator with low viscosity, low HTHS oil. The load of water heaters which draw 4500W, or way more for instant hot setups can be a big drain. Add in AC, fridge, and well pump and we have a great way to push an air cooled engine into high oil temps. What I'd aim for in an automatic start to full RPM type unit, is an oil that has a very low pour point and excellent HTHS. In other words, a very high quality synthetic. Amsoil, Redline, HPL and a few flavors of Mobil 1, if they work with the engine's configuration/propane/NG/gasoline etc.

 

[loneryder]

Generac's brand of 5W-20 synthetic oil states it is a low ash (low SAP) oil designed for gaseous engines, apparently for deposit control (Generac 5W-20 label). A VOA bears this out showing relatively low CA and ZDDP levels (Generac 5W-20). Their literature only states oil recommendations, not requirements, so there is flexibility in viscosity. I will be using Mobil 1 ESP 5W-30 (lower SAP) in my new Generac 26kW generator as I prefer a higher HTHS viscosity for this air cooled engine.

My post in a previous thread repeated below:

I just had a Generac standby 26kW whole house propane generator installed last week. The owner's manual sets no requirements for the oil! It just says that "All Generac oil kits meet minimum API Service Class SJ, SL or better" and "It is recommended to use Generac's proprietary 5W-20 gaseous engine oil for continuous use".

Their website, however, recommends "Generac 5W-20 full synthetic oil for all home standby generators, no matter the temperature", but also allows a straight 30, a 10W-30, and a synthetic 5W-30 for specific temperature ranges. All recommendations, no requirements.

Generac Oil Recommendations

Just in time Tom! You are going to need it.

 

[Tom NJ]

Just in time Tom! You are going to need it.

Yes, I expect some utility power loss with this storm, which looks like a mix of snow and ice here.

 

[locomaster1969]

I use Mobil 1 or Castrol EDGE 0w40. Easy cranking in cold winter and god protection in hot weather.

Mobil 1 0w30 also works really good.

 

[wavinwayne]

Yes, I expect some utility power loss with this storm, which looks like a mix of snow and ice here.

In the forecast models early this week, we in North AL were on the southern edge of the expected ice, but the current models now have most of the nasty stuff staying north of us. I hope you get through it with minimal disruptions.

 

[k1xv]

A question:

How many outages do you get in a typical year, their duration, and do they occur mostly in cold weather, or warm weather?

Seems to me there is a potential difference in recommendation based on whether the generator must run in the heat of summer, cool of winter, and whether ease of starting is ever an issue. For example, I would want a thicker oil if it had to run for hours and hours in the summer, but thinner oil if it had to start in freezing weather.

 

[k1xv]

I now avoid these issues. Instead of a generator, I have two Tesla Powerwalls.

 

[Saturnguy]

Mobil 1 ESP 5W-30 and OW-30 also have an ACEA “C3” light diesel rating…

 

[Tom NJ]

In the forecast models early this week, we in North AL were on the southern edge of the expected ice, but the current models now have most of the nasty stuff staying north of us. I hope you get through it with minimal disruptions.

Thanks! A couple of days ago they had us expecting 2-3 feet of snow, but since the path has shifted north a bit our current forecast is for 7-10 inches of a wintery mix. Just changed the oil and started up the snow blower in preparation.

 

[Tom NJ]

A question:

How many outages do you get in a typical year, their duration, and do they occur mostly in cold weather, or warm weather?

Seems to me there is a potential difference in recommendation based on whether the generator must run in the heat of summer, cool of winter, and whether ease of starting is ever an issue. For example, I would want a thicker oil if it had to run for hours and hours in the summer, but thinner oil if it had to start in freezing weather.

Not sure who you are asking, but in my case we get numerous short outages (seconds to a few minutes) throughout the year, but long outages are generally caused by ice storms in the winter. I had the generator installers set the generator to wait five minutes before coming on so as to skip the many short interruptions. This also gives me time to throw the circuit breakers on some of the heavy power users so the generator doesn't have a heavy load on startup, then switch them back on one at a time. As for oil, Mobil 1 ESP 5w30 satisfies both summer and winter usage.