I have a 4.5 liter 4 cylinder water cooled engine running natural gas in a Generac generator. I was considering AMSOIL Signature Series but Amsoil tech department said I should use the OE because it is low ash and the SS is not. Even though the manual does not mention a low ash requirement, I contacted Generac and they pointed out that I should indeed use low ash 5w30 SN or later oil and that their own oil is low ash and should be the oil of choice. Is there any research to support the need for low ash oil in natural gas engines? It looks like the best synthetics from most companies are not low ash. One interesting exception is Fuchs GT Flex C23 5w30 that is not only low ash but even states for use in gasoline, natural gas, and diesel engines. Any thoughts on using one of the high end oils SP or SQ and disregarding the ash content?
Low Ash Required For Natural Gas Engine?
- Thread starter GJ1951
- Start date
Does it have a catalytic converter or DPF?
Valvoline Premium Blue One Solution calls out Natural Gas for it's application.
Ash 0.9%
https://sharena21.springcm.com/Publ...2d889bd1/e68a6c51-a070-ea11-9c34-ac162d889bd1
https://investors.valvoline.com/new...iesel-and-Gas-Heavy-Duty-Engines/default.aspx
10w-30
https://sharena21.springcm.com/Publ...2d889bd1/e68a6c51-a070-ea11-9c34-ac162d889bd1
15w-40
https://sharena21.springcm.com/Publ...2d889bd1/138b6c51-a070-ea11-9c34-ac162d889bd1
Ash 0.9%
https://sharena21.springcm.com/Publ...2d889bd1/e68a6c51-a070-ea11-9c34-ac162d889bd1
https://investors.valvoline.com/new...iesel-and-Gas-Heavy-Duty-Engines/default.aspx
10w-30
https://sharena21.springcm.com/Publ...2d889bd1/e68a6c51-a070-ea11-9c34-ac162d889bd1
15w-40
https://sharena21.springcm.com/Publ...2d889bd1/138b6c51-a070-ea11-9c34-ac162d889bd1
No it does not.
Yes I had considered that oil but Generac said considering winter in Wisconsin not to go beyond 5w30.
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i thought most of the new Generac's take a 5W20 full synthetic. i would go with a full synthetic from Mobil 1, Castrol or Pennzoil. Pennzoil Platinum and Ultra Platinum are very clean oils.
Here is the relevant page from my owners manual. This is a relatively large 48kw generator with a 3 gallon oil capacity. Contacting Generac tech support, they emphasized the low ash requirement and 5w30.
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- Jul 28, 2024
- Messages
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Walmart or any auto parts store get a 5W30 full synthetic no need to worry about low ash etc… if you notice any hard starts during cold winters you could look into the block heater kit.
Tom NJ
$100 Site Donor 2026
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
Apparently the engine is not very sensitive to viscosity or API Service Class. Mine will get Mobil 1 5W-30 API SQ after the 25 hour break-in.
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
Apparently the engine is not very sensitive to viscosity or API Service Class. Mine will get Mobil 1 5W-30 API SQ after the 25 hour break-in.
It must be different recommendations for air cooled. The viscosity chart from my manual shown above has only 5w30 for all temperatures. I also contacted Amsoil, Valvoline, and Royal Purple tech. RP said they do not recommend any of their oil for natural gas engines. Amsoil said only their OE oil should be used because it is the only low ash oil they sell. Valvoline said all of their oils are low ash and recommended their Restore snd Protect Stnthetic.
I'm running Mobil 1 ESP 0W30 in my 18Kw Generac now after I passed the 25-hour break-in period.
Advertised as low ash content (Features) on the website: https://www.mobil.com/en/lubricants/for-personal-vehicles/our-products/products/mobil-1-esp-0w-30
Advertised as low ash content (Features) on the website: https://www.mobil.com/en/lubricants/for-personal-vehicles/our-products/products/mobil-1-esp-0w-30
From the Natural gas oil Amsoil carries in 5 gall pails. They show two of them. Too bad they only sell it in 5 gallon pails.
Looks like one is a 15w-40, and the other is a 20w-40
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is formulated specifically to meet the special requirements of natural gas fueled engines used in vehicles and mobile equipment. It delivers superior protection and performance in applications calling for a 15w-40 low-ash lubricant.
The synthetic base oil and advanced anti-wear additive system of Synthetic Vehicular Natural Gas Engine Oil provide enhanced valve train protection, whether roller or slider followers are used. It is formulated with high levels of zinc and phosphorus to provide outstanding wear protection in applications requiring the Cummins CES 20074 specification.
Minimizes Deposits and Valve Recession
Synthetic Vehicular Natural Gas Engine Oil's low-ash formulation helps minimize valve stem and combustion chamber deposit formation. It is designed to reduce valve recession, a common problem with low-ash oils. Its balanced formula allows for a high total base number (TBN) to neutralize acids and protect against corrosion while meeting low ash requirements.
Maintains Viscosity
The shear stable formula of Synthetic Vehicular Natural Gas Engine Oil offers maximum protection against viscosity loss while providing optimal service over a broad temperature range. It has inherently low volatility to reduce oil consumption and emissions, helping maintain serviceability of emissions equipment.
Delivers Continuous Protection
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is a long life oil that has demonstrated extended drain interval capabilities when carefully monitored by an oil analysis program. When extending oil drain intervals, change the oil filter at the engine manufacturer's recommended interval.
Applications
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is recommended in mobile applications fueled by compressed natural gas (CNG), liquefied natural gas (LNG) or liquefied petroleum gas (LPG); including transit buses, medium/heavy duty trucks, refuse haulers, school buses and delivery trucks. It is formulated for applications requiring the Cummins CES 20074 specification.
Mixing AMSOIL
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is compatible with conventional petroleum oils and other synthetic lubricants; however, mixing AMSOIL with petroleum oil will not allow for the maximum protection and performance of the product. Engine oil additives or aftermarket products are not recommended for use with Synthetic Vehicular Natural Gas Engine Oil.
Looks like one is a 15w-40, and the other is a 20w-40
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is formulated specifically to meet the special requirements of natural gas fueled engines used in vehicles and mobile equipment. It delivers superior protection and performance in applications calling for a 15w-40 low-ash lubricant.
- Guards against valve-train wear
- Fights valve recession
- Helps reduce oil consumption and emissions
- Capable of extended drain intervals with oil analysis
The synthetic base oil and advanced anti-wear additive system of Synthetic Vehicular Natural Gas Engine Oil provide enhanced valve train protection, whether roller or slider followers are used. It is formulated with high levels of zinc and phosphorus to provide outstanding wear protection in applications requiring the Cummins CES 20074 specification.
Minimizes Deposits and Valve Recession
Synthetic Vehicular Natural Gas Engine Oil's low-ash formulation helps minimize valve stem and combustion chamber deposit formation. It is designed to reduce valve recession, a common problem with low-ash oils. Its balanced formula allows for a high total base number (TBN) to neutralize acids and protect against corrosion while meeting low ash requirements.
Maintains Viscosity
The shear stable formula of Synthetic Vehicular Natural Gas Engine Oil offers maximum protection against viscosity loss while providing optimal service over a broad temperature range. It has inherently low volatility to reduce oil consumption and emissions, helping maintain serviceability of emissions equipment.
Delivers Continuous Protection
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is a long life oil that has demonstrated extended drain interval capabilities when carefully monitored by an oil analysis program. When extending oil drain intervals, change the oil filter at the engine manufacturer's recommended interval.
Applications
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is recommended in mobile applications fueled by compressed natural gas (CNG), liquefied natural gas (LNG) or liquefied petroleum gas (LPG); including transit buses, medium/heavy duty trucks, refuse haulers, school buses and delivery trucks. It is formulated for applications requiring the Cummins CES 20074 specification.
Mixing AMSOIL
AMSOIL Synthetic Vehicular Natural Gas Engine Oil is compatible with conventional petroleum oils and other synthetic lubricants; however, mixing AMSOIL with petroleum oil will not allow for the maximum protection and performance of the product. Engine oil additives or aftermarket products are not recommended for use with Synthetic Vehicular Natural Gas Engine Oil.
Just run the 5-30w synth. oil if you have a cold weather kit installed. Otherwise no cold kit run the Mobil 1 0w30. Your in Wisconsin, it gets really cold in winter and hot in the summer so you want an oil that will cover you temperature range. No need for overpriced ''boutique'' oils.
I've been running Walmart SuperTech 5w30 in 2 different units for decades now with no issues. -20f to 90f temp. range here.
I've been running Walmart SuperTech 5w30 in 2 different units for decades now with no issues. -20f to 90f temp. range here.
I had hoped to find an oil like those in 5w30. The 5 gallon pails would not be a problem since it takes 3 gallons each oil change. For some reason Generac recommends SN or newer spec rather than any oil made specifically for natural gas engines.
Just received an updated response from Castrol.
Which means nothing of any importance.
Go to Walmart and buy Mobil 1 ESP 0W-30 as already noted. Low ash, universal winter rating, and minimum 3.5 HT/HS for the summer. $27 for 5 quarts of a world-class oil.
