No, propane power doesn’t make oil honey-thick

February 1, 2012 | By Richard Prince


I would like to comment on your answer to Pete Reiland about converting a vehicle to propane fuel (September). Your answer to Pete’s question was accurate but I think it should have included information about propane’s effect on motor oil. Regular oil will eventually develop the viscosity of honey. This problem kept some truck manufacturers from offering a propane option. The same problem exists with natural gas. Now, special oils are available. If this had been included in your reply, the owner would have been aware before he even started the conversion.


Thank you for taking the time to write in. After doing quite a bit of research the old-fashioned way and on the Internet, and speaking with product experts from Chevron, Valvoline and Exxon Mobil, I could find nothing to substantiate your assertion that regular oil will eventually develop the viscosity of honey if used in an engine fueled by propane.

The American Petroleum Institute, which has been a leading organization setting motor oil standards since 1924, does not have a distinct standard for oil to be used in LNG or propane-fueled vehicles.

Most of the major oil companies do market oil specifically for LNG vehicles and in all examples I’ve found the major difference between these LNG-specific formulations and their gasoline engine counterparts is the amount of ash. Ash is potentially detrimental to certain modern emissions control devices, including catalytic converters and particulate filters commonly found on newer diesel vehicles, so the low-ash oil reduces the chance of damage to these components.

If you convert an older car to run on propane you won’t harm it by using an engine oil formulated and marketed for LNG-fueled vehicles but at the same time, you won’t harm it by using an engine oil formulated and marketed for gasoline fueled vehicles.

If you have a newer vehicle stuffed with emissions control systems then I’d recommend using the low-ash formulation whether you’re powered by gasoline or propane. If you have an older, pre-emissions controls vehicle that’s been converted to run on propane then there is no harm in using a low-ash oil marketed specifically for LNGand propane-fueled engines, but there is apparently no harm in using oil that’s not specifically marketed for LNGand propane-fueled engines.