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Old 08-18-2011, 12:07 PM   #1
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Mobile 1 Synthetic vs OnaMax Generator Oil

I am in Florida and I am the proud new owner of a 2001 Class C Coachmen 30.6' Leprechaun - nice RV. Low miles. Well anyway, it is time to change the oil in the generator which is a MicroQuiet 4000...the one with no oil filter and it has 406 hours. Runs like a champ. Well anyway just want to change the oil and would like to use a Synthetic and I found this article.....and just wanted to get some other opinions -

Question: Is There a Mobil 1 SAE 30 Oil that Will Handle Generator Requirements?I have a Generac 20 KW Natural gas generator with a 36 horsepower V-Twin aluminum engine that recommends SAE 30 Oil for protection from 32° to 110°F. According to my manual SAE 10W-30 only protects from -10° to 40°F. Amsoil (Formula 4 stroke 10W-30/SAE 30 Small Engine Oil) is the only oil that I can find that meets the requirement. I have always used Mobil 1 and now use Mobil 1 Extended Performance in all of my automobiles and lawn equipment. Is there a Mobil 1 full synthetic oil that I can use in my generator and still meet the SAE 30 requirement. I live in south Louisiana and temperatures reach a 100° but also needed the generator in 20° weather last winter. The recommended oil change is 2 years or 200 hours.-- Sal Mike, Hammond, LA

Answer: We recommend you use Mobil 1 5W-30. It protects well over a wide range of temperatures and outperforms conventional oils.

Thanks and I am looking forward to your replies!

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Old 08-18-2011, 12:30 PM   #2
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Tony: Generally speaking, it's not always good to go with a full syn oil after so many miles (cars/RV's) and hours (gen). There are a lot of reasons not to do this.

I would suggest, maybe, use a blend of regular oil and syn oil first. See how that works for you. At the first sign of trouble, drain, go back to regular oil.


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Old 08-18-2011, 03:41 PM   #3
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Originally Posted by two-niner View Post
Tony: Generally speaking, it's not always good to go with a full syn oil after so many miles (cars/RV's) and hours (gen). There are a lot of reasons not to do this.

Since when is 400 hours "so many" on a generator?
John Day....|'88 Winnebago Super Chief 27ft. Class A
Eastern .....|'88 KIT model 240 24 ft. 5er
Oregon ......|'02 Dodge/Cummins 2500 Quad Cab
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Old 08-18-2011, 04:12 PM   #4
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For your temperatures Owen recommends 15W-40
It is a air cooled engine just like a Harley Davidson.
Mobil 1 has a 20W-50 for air cooled engines
99 Discovery 34Q ISB
2014 MKS AWD EcoBoost Toad
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Old 08-19-2011, 11:24 AM   #5
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Ordinary (dino) oil builds up a coating on the valve seals. Occasionally, the seal has a little damage that dino oil will "heal" and the engine continues to hum along.

Switching to syn oil will clean the coating off, that's syn oil job, and the seal will leak.

OP stated his generator "is running like a champ".

I know, I know, billions have switched ten year old generators from dino oil to syn and had no problems.

I'm not sure why my second paragraph was not in the quote in post #3. That's the key piece of the response.

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Old 08-19-2011, 01:37 PM   #6
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Use your manufacturer recommended viscosity. Synthetic vs Dino. You make that choice. Most concerns about switching from dino to synthetic oil have proven to be myth.
Charlie & Sherrie
Southeast Texas
'99 Southwind Storm, '10 Honda CRV
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Old 08-19-2011, 02:14 PM   #7
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the mobil 1 website has a wealth of information on all their various products. also bobistheoilguy.com

biggest problem is not viscosity level but cold start and high pressure point wear performance.

Since generators do not have a cat and they don't hold a lot of oil, something like Mobil-1 4T has a lot more ZDDP and will protect the cam better. It's $10/qt but it's not like you're going to use a lot of it.

Also Valvoline NSL 20W50 if you are't running in cold temps.
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Old 08-19-2011, 02:36 PM   #8
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I've been running Mobil 1 10W-30 in my Onan for years, we never camp in temps below 70F.
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Old 08-19-2011, 06:49 PM   #9
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can I use my harly 15w40 in my onan that is 34 yrs old and 40 some hr's? thanks

John & Colleen Weston & Cassie(our cat) -Olympia,WA
1978 GMC Midas Class A 30FT-454 Engine, 400 T
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Old 08-21-2011, 07:45 AM   #10
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There is some bad info in that quote. If 10w-30 only protected from -10 to +40 most of the cars on US highways would have seized engines. SAE 10W-30 has the same high end temp range viscosity as plain SAE 30 - that's what the SAE"30" spec number means. 10W-30 acts like 10 weight when its cold and 30 weight when it is hot.

But you don't need the "10W" rating unless the engine will be run in very cold weather, below 32 degrees. Plain SAE 30 is fine down to about 32 degrees.

Onan likes SAE 15W-40 for temperature extremes; otherwise they recommend SAE 30 for their gas engines.
Gary Brinck
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Old 08-21-2011, 10:01 AM   #11
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10W-30 should be fine for your generator at your location in La. You don't have low temperature extremes to warrent any lower viscosity. Even a 15W-40 would work as well.

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Old 08-21-2011, 10:19 AM   #12
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Good forum on lubricants of all kinds and applications

I find this is the best lube site Ive found so far,
Its self explanatory

i read in there somewhere by an "expert" that started the site,that the lower the first # eg 0-30 ,5-30 is best as it promotes start up lube sooner than the first # that are higher.
its hard to find lower numbers than 0

Bob Is The Oil Guy - Forums powered by UBB.threads™
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Old 08-21-2011, 10:35 AM   #13
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Biggest problem with multi-grade oils, is that the actual volume of the lubricant is diminished by the volume of the stabilizers required to extend the the temperature vs viscosity range involved - and that percentage CAN be pretty high. In that case, 30% of what you are buying in a bottle of oil may well be a non-lubricating stabilizer element that you don't really need, and is NOT providing any actual lubricant properties.

That stabilizer MIGHT be needed in areas of the country, or equipment types operating in wild swings of temperature - otherwise, if NOT needed in those conditions, you get lots more actual lubricating for your $$$ in a non-stabilized, single weight oil - whether it's a vehicle engine, or a generator.
John Day....|'88 Winnebago Super Chief 27ft. Class A
Eastern .....|'88 KIT model 240 24 ft. 5er
Oregon ......|'02 Dodge/Cummins 2500 Quad Cab
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Old 08-21-2011, 10:43 AM   #14
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if you look at alot of new cars they run 5w20 both my new ford foucus, and 2010 dodge caravan,

in winter I run 0w40 in my conversion bus(7.3powerstroke) and in my work truck I run 0w40 all year long (syn) 180kms no problems.
gets real cold here -30 - 40 c
in my genertors 5w40 syn some times 0w40 depends what I have.

anyway the low end of the oil makes start ups easyer, and faster lubercation to all parts of the motor which is what you want, sometimes you can start a motor and you hear tic tic (valves etc) for a few seconds, I dont get that useing syn oil, also syn oil can take the heat, and have additives to help seal oil leaks. when you go to syn oil, also you can extend oil changes (I change reg) if you want, dino oil will be a thing of the past, you see it all ready with prices going down. (on syn oil)
just my 2 cents don t want to start a pee match

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