Best oil for a Generac generator

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I have a Generac generator that has a 30 hp V-twin air cooled engine, I am wanting to know what would be the best oil to use in it. I do not use it much, so it sits a lot of the time, but when I do use the generator it is in the winter time and spring. So the the operating temps are normally cool to cold. The oil that I am using right now is Mobil 1 5w30w truck & suv. Thank you for all your help.
 
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Might be worth getting an IR gun to get the heat off the engine block and cooling fins. (or out of the oil sump). I bet it has a more than adequate fan.

My aircooled motorcycle runs 205'F on a 75'F day though it's linear so ten degrees more outside make it run that much hotter. 205'F is good 30 weight territory.

Does it have auto start and switchover? The 5w will be good for that load that hits it seconds after getting up to speed. And the extra additives make good preservative for sitting. I can't argue with your choice unless it gets super duper hot.
 
I put Amsoil 0W-40 in mine. Have checked the temperatures at the oil filter a few times, but it has never been over 40 degrees ambient temperature outside, the temps I got were near 175 with running 30 minutes wide open loaded up. Did notice at the oil cooler the temperature dropped about 15 degrees from one side to the other.
 
It does not have auto start or switchover. I usually start it and let it idle for about five minutes before I put a load on the unit. I have not checked it with a IR gun, since I do not have one, but one thing in my favor, it does have a oil cooler on it.
 
I have a friend that is a certified Gennerac tech. He uses nothing but M1 5-30 in all of his PMs. What you are doing will work well for you.
 
I have that same Generac engine in a 6 year old, 13 kw, natual gas fueled, auto start version. So I will tell you what I know.

All the Generac techs (and the book) recommend Mobil 1 5W30. In my experience, it is a good all purpose oil. There is a Generac forum. In it, some owners complained that Mobil 1 5W30 tends to be "consumed", or burns off during an extended power outage (longer than 40 hours of continuous operation). When that happens, the low oil level causes the generator to automatically shut off to prevent engine damage.

We have had 48 hour power outages in both 90F and 5F temperatures. Since I am not a fan of refilling a generator's oil level in a blizzard, I decided to switch to an oil that
is a bit more "stout" than a thin, car oil. In the winter, I use Castrol 0W30. In the summer, I have been using Amsoil MCT 10W30 motorcycle oil. During summer temperatures, I have also used straight 30 weight. It is cheap and works well. So far, no problems here. These synthetic oils might sound like overkill, but I know one thing; If I am out of town, and the power is out for several days, my wife will not fool around with a generator, to see why it shut itself off. She will go to a hotel instead.
 
Originally Posted By: greenaccord02
I'd get a xW-40 HDEO. You need something that will stand up to some shear.


Like Mobil 1 Turbo Diesel&Truck or Rotella T6 @ 5w40?
 
Originally Posted By: willix
You want an HEDO such as Delvac or Rotella in a 10w30 for a air cooled engine.

Are there cold starting issues with that choice? I sure like their protection and shear stability, though.
 
I was considering a 5w40w like rotella but in the owners manual it made it clear not to use a 10w40w, so I thought that a 40w would be to heavy since they said a 10w30 was alright on temps above 50 degrees.
 
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I poured in RTS 5W-40 right after breakin on my Generac... I've only had to use it 2 times this winter for a period of 24 hours... Our local Oriellys just started stocking M1 0W-40... After doing some reading on this oil... It seems it's one of M1 more robust oils... Only thing is... complaints of it shearing fairly easy... Any thoughts on this oil choice?
 
Mobil 1 0w40 would be an excellent choice. I plan on using it in mine after break in. As for shearing, i think it's just perfect. If it shears, it will still be in the 30 weight range, where a 30 to start with might end up a 20.

Use it longer though since it's synthetic to get good money from it. There's a UOA somewhere from i think it was a honda gx340 on 0w40, 312 hours and it was good.
 
Originally Posted By: kdoss
I was considering a 5w40w like rotella but in the owners manual it made it clear not to use a 10w40w, so I thought that a 40w would be to heavy since they said a 10w30 was alright on temps above 50 degrees.



Did they specify whether that was a conventional 10w40 or a synthetic 10w40?? In most cases its a cold weather thing with a conventional oil, and a synthetic might be OK in the same viscosity.

I recently went through this same exercise, and after a little research decided on 5w40 Schaeffer Series 9000. It has (what looks like to me) good cold weather characteristics, and the durability of HDEO.
 
I have the 3.0 L six which is bascially a ford taurus engine. The manual states 15w-40 in temps 80 and above (applicable for me). All the 15w-40 stuff i see is labeled for diesel. For this application does anyone see an issue with using 5w-40 synthetic? fyi, the api ratings in the manual call for CC, SD, SE, OR SF which all seem to be outdated, so I'm gathering any oil sold today has adequate ratings.
 
I would think Mobil 1 0W40 would work great in a generator type application. Change it once a year... Only change it more if the generator is working long hours/days in an extended power outage.
 
Sounds like you are using an excellent oil for your application. Robust, capable of extreme temperatures, excellent cold flow characteristics, available anywhere.
 
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