Which oil to use in my generator Is SJ better

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Jan 2, 2020
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Cedar Rapids, IA
Just purchased a Generac 8000-10000 watt generator because of the inland hurricane here in Iowa. Oil is scarce at the moment so my options are royal purple 30w SJ, Castrol dino 10w30, or Pennzoil 5w30 SN synthetic.

The manual calls for generac 5w30 oil for colder temps and straight 30 for higher temps but makes no mention of rating (sj, sm, sn, etc)

It's going to be 80-90 degrees here so I want something that is not going to burn my engine up.

have read the SJ oils are not API certified because of high Zinc content. Which theoretically would be better.

Any insight on this?
 
API SN has usually ZDDP content around 700-800ppm.....look it up in VOA/UOA section of that forum...

So use sae30 or 10w30
 
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Of the three oils you listed, I would go with the Pennzoil 5w30 synthetic. A quick internet search on Generac 5w30 reveals that the Generac 5W30 is SN rated.
 
I use Rotella T6 5W-40 in my small 2,200W generators.....I use that oil for all my lawn equipment and my Motorbikes too....it is JASO compliant.
 
Just purchased a Generac 8000-10000 watt generator because of the inland hurricane here in Iowa. Oil is scarce at the moment so my options are royal purple 30w SJ, Castrol dino 10w30, or Pennzoil 5w30 SN synthetic.

The manual calls for generac 5w30 oil for colder temps and straight 30 for higher temps but makes no mention of rating (sj, sm, sn, etc)

It's going to be 80-90 degrees here so I want something that is not going to burn my engine up.

have read the SJ oils are not API certified because of high Zinc content. Which theoretically would be better.

Any insight on this?
any of those oils will be fine but I would go with the castrol for initial break-in, run it under a variable load for 5 hours then change it with any of the oils you listed.

A toaster oven does a pretty good job as a break in appliance as it cycles on and off at the set temperature, but any electrical resistive heating element that will cycle will also work
 
In my Generac, I've always used 5W30 Mobil 1. Couldn't be happier. Had it for over 12 years now and still runs like a new one.
 
After the tornado in CT our standby generator ran under load for 41 hours straight. (Except for a brief shut down to check oil level) It is a Briggs & Stratton 31000 500cc engine. It burned 1/3 quart of oil in a 1.5 qt sump. OAT averaged 70-85 degrees. I drained the oil still warm from the run. It was thick and drained slowly. Havoline DS Full Syn 10W30. The plug was fouled badly too. Replaced with RGT 5W30 for winter months per manual.

I’m having second thoughts on the 5W30. Leaning towards replacing it with AMS Small Engine 10W30.
 
Now that things are back to semi-normal, I now have a plethora of oil available now at my disposal and since my prepper OCD is kicking in full gear I'm thinking of running my two generators, honda power washer, and push mower all on 10w30.

I've looked at VP racing small engine oil, Amsoil Signiture (SN) series, and Amsoil small engine oil. Trying to determine which would be the best.
I'm getting all caught up in the SN and SJ ratings. I've been told the small engine oils are SJ rated because of the high zddp and therefore cannot meet modern API requirements because of damaging catalytic converters. Seems like the SJ oils would lubricate better but at what cost to modern small engines. I also have a new Honda eu2200i I got from insurance.
 
I've got about the same mix and I've been using Mobil 1 10W30 for a lot of years now. No problems at all.
 
My experience with air cooled engines is rather extensive. I have rebuilt and repaired many commercial mower engines. I have rebuilt engines with 3000+ hours which is quite rare. The constant factor was Mobil1, checking the oil daily, and changing oil at 100 hours. For your application using synthetic I suggest Mobil1 10w30 or 10w40. Amsoil is arguably the best oil for this application however it is not readily available unless you have a dealer nearby. Mobil1 in many flavors in a 5 qt jug is 22.99 at Walmart. Another option is conventional diesel oil in Straight 30 or 15w40. Any brand is good. High zinc level will protect internal moving parts. High level of detergents to keep internals clean. Holds up well to heat, extended runs, temperature extremes.
 
Thanks locomaster
I usually get Mobil 1 oils and run them in my cars. Amsoil be just as cheap around here so when I get a pretty good deal, I stock up. I don't have a preference in oils, just want my equipment (mainly generators, I run medical equipment off of them) to be reliable and last a long time. With temps in iowa ranging from -20 in the winter to 90's in the summer I want to cover all my variables. After the storm we had, I'm installing a transfer switch to my house so I can run a washer, medical equipment (O2 machine and Bipap) a dual door fridge/freezer and furnace in the winter.
 
I have been running the Amsoil small engine 10w30 in my generators and other small engines for 14 years with good results.
Little to no oil consumption, and anytime I have pulled a valve cover for a valve adjustment, the engine is spotless inside.
And if you are a preferred customer, the price is not bad either!
 
Rotella T6 5w40 synthetic is my go-to for generators, and any 15w40 is what I use for engines run mostly in the summer. These oils are stout, cheap, and easy to obtain. While there is nothing wrong with Amsoil, I really hate buying boutique oils I can only find online for small engines. What happens if you need more to top off? Do you order extra or just throw in what you have on hand?

I run a small engine shop as a side business, and have never had an issue with Rotella T6 5w40 or any HDEO 15w40. I run the 5w40 in my own generator with a flathead 8hp Briggs.


Edit: apologies, I'm an idiot. I think I read another thread asking about generator oil and responded to this one. :LOL:

Any of the oils you listed will work perfectly fine. The SAE 30 would probably be more resistant to shear and would be my pick, but any of them will work well as long as you check the oil just in case it burns any.
 
I have run M1 10w-30 High Mileage (HTHS 3.5) and Rotlla T6 5w-40 in both of my generators. Currently both have the T6 in the sump. We've not had an extended power outage in a while, knock on wood. Should we have one I can alternate between the two for cooling, fueling and oil changes. Alternatively I can loan one to a neighbor in need.

This is highly subjective, but I think the Predator 3500 sounds a little better on the M1. As I said, highly subjective. I wouldn't hesitate to run either of these oils in a generator.
 
I think vp racing small engine oil is sn oil with little to no VI but base oil is group 3 with little to no ester oil, it will better to go with amsoil small engine or any other brand you like except vp racing since you pay for brand name
Now that things are back to semi-normal, I now have a plethora of oil available now at my disposal and since my prepper OCD is kicking in full gear I'm thinking of running my two generators, honda power washer, and push mower all on 10w30.

I've looked at VP racing small engine oil, Amsoil Signiture (SN) series, and Amsoil small engine oil. Trying to determine which would be the best.
I'm getting all caught up in the SN and SJ ratings. I've been told the small engine oils are SJ rated because of the high zddp and therefore cannot meet modern API requirements because of damaging catalytic converters. Seems like the SJ oils would lubricate better but at what cost to modern small engines. I also have a new Honda eu2200i I got from insurance.
 
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