I have been testing Lehr units (www.golehr.com
) for about a year now. I had a problem with too much oil in the system (all four stroke) but the company has fixed this, they changed the recommended level of oil. The handheld equipment (trimmer, edger and blower all run on just about an ounce of oil in the sump. The company recommends changing the oil a little more often since I am using these units for commercial use but I see that the oil is very clean even when I change it. I have been told propane burns up to 93% cleaner than gas and this will increase the engine life.
I have not been able to see much of a difference in torque or power becasue I really don't have a side by side test with equipment the same size (engine and design). I have read that there is a slight decrease in horsepower but nothing major to write about. It is nice being able to pull the string and start using it. I hardly have to let it warm up and it seems to start almost every time. Not having to mix gas, spill gas or carry two, three or more different gas cans is nice as well.
I have been a certified mechanic for over twenty years so I do all my own work and adjustments as it is recommended to check and adjust the valves every 25 hours as well. The owners manuals explain this in detail and provided you know the right end of a screwdriver to use you should be able to do this adjustment yourself. If you are nervous about doing this it might just be better to take into a local shop and have them do it, it would be better to make sure your equipment stays running in top condition. I am also working on putting a conversion kit on my 36" walk-behind. I bought the conversion (forgot the company's name but can get it if someone really needs it) for the exact engine I will be putting it on. Propane does not seem to be very difficult. If you are familar with the mechanics of equipment it is not much different. Propane is a drier fuel but the benefits seem to outweight the cons. Most of these fuel systems are a pressurized type fuel system with low pressure. If I remember correctly pressure is somewhere between 8-18 psi. You need to remember to disconnect the propane can or shut off the valve because if you don't you could empty the can overnight or over the course of a long day.
I think that is about it for now. I will keep testing (and using) propane equipment and I think over the next couple of years propane equipment will continue to improve. While I like the Lehr handhled equipment I would like to see someone else offer their own version. We are starting to see more and more propane mowers and if I can swing it I am planning on going to the GIE Expo this year to see the latest and greatest items manufactures have to offer.