i got a big oil use issue with a Kohler twin SP27 using a lot of oil and fowled plug on the the oil cap side of the engine. FYI, i read somewhere on the net to check the reed valve- whatever that is- a busted or defective one leads to excessive oil use apparently. Anyway, my low oil pressure light was not working from the start, and i ran mine with low or no oil - real smart i am. Now, i am looking for a short block to get me going again. the thing runs but uses an unsustainable amount of oil because the oil rings on the piston and bore are probably damaged - i think. As i have to add oil again after a couple of hours hard running, and even one cylinder stopped firing because of the oil on the plug. I think the compression and oil rings are gone, and it would have been due to running it on a hot day/week with low oil, from what i am recollecting about the machine usage and engine noises. the machine was showing 20% pressure loss on one side, after only 200 hours. Another veteran mechanic said that all air cooled engines all use some oil as a part of normal running, and that it is important to keep an eye on your oil levels at all times, or you will get what i got. The mower repair guys said i 'dusted' the engine by not maintaining clean air filters, but i am pretty certain i damaged the engine rings and bore because of low or no oil. i am going to order a new engine from the USA , and have the old one rebuilt in a engineering shop that specializes in cylinder sleeves and pistons. Its an expensive pain in the rear but, having a spare good engine block ready to go is the only way i can think of to control the engine reliability situation long term .

You can run any of the oils mentioned, Straight 30w only in summer if you run you LT in the winter months then it would need thinner Weight. It's not problem after the engine heats up, but start up on cold or cool days. Once the 30w get hot is runs like water anyway. Syn oils could be left in little longer, but when it gets black and gooey and don't drip off the dipstick it needs changed. IMO you should change the oil at least twice a year and the filter once a year. THE idea is to have clean oil in your engine during the hot summer months when it works the hardest. If you are in good non-dusty conditions then the oil will stay cleaner longer. IMO you should change your oil in MAY at the beginning of the summer, in mid or late JULY when it really hot, and in sept/oct. with the filter. If you do that you will probably never experience a oil related problem (unless you over fill it or run it low on oil) and your mower may not use oil between oil changes just like you have already experienced with the JD.

***"If it was burning oil I'd think I'd get a consistent black smoke?"*** No. Gasoline overfuel (or excessively rich) causes black smoke because of the very "complex" way gasoline burns, or "combusts" in the combustion chamber, because of the "complex chemical make up", of gasoline. Gasoline, Diesel "fuel oil", and engine lube oil, are all in the family of chemical compounds we call Hydrocarbons. Hydro for Hydrogen and carbon for Carbon. Hydrocarbon compounds are made by combining "elemental Hydrogen" and "elemental Carbon" together. Because hydrogen and carbon can "link up" in very complex combinations (compounds), these combinations are called "chains". How many atoms of each element, and the varying ways they alternate and hook up determines the "properties" of the final compound. Some of the resulting combinations are very "stable" and DO NOT want to evaporate (or even "melt") easily. Other combinations will "flash" at low temperatures and remain "a thin liquid" at extremely low temperatures. One thing all hydrocarbon compounds share is "combustibility". The ability to combine with oxygen (or "burn"). Some hydrocarbons are eager to combust and only need to get near a "molecule" of oxygen and they just "throw open their arms" to the oxygen (very "promiscuous"). Other compounds are so reluctant to "mess around" with oxygen that they must first be heated to a high temperature before they'll have anything to do with any oxygen molecules (or oxygen atoms). You can draw your own analogies there, but suffice it to say, these compounds are very "chaste". Ok, lets use this in a practical way now. Starting with "how come "burning oil" makes BLUE smoke. The short "answer" is: Because the oil "ain't actually burning". Some portion of the oil (in an engine that is "consuming oil") does actually burn, but the majority of THOSE hydrocarbon molecules are only "vaporized" by the heat of the combustion chamber environs. The hydrocarbon compounds that make good "lubes", are some of those "chaste", or stable ones that don't enjoy "a good combustion". The color of lube oil "vapor" in an exhaust plume is similar to to what you would see if you poured some oil on a hot exhaust manifold. Starting a Diesel engine in frigid temps will result in the following observances in the exhaust plume: First, you will see the fuel oil "vapor plume" as a white or blue/white color, because the initial heat of compression, is only hot enough to vaporize a portion of the Diesel fuel oil, but not hot enough to "ignite" (flashpoint temperature) the fuel. The next color change will be the addition of black as the combustion chamber temperature begins to reach "ignition" flashpoint. But, even though ignition has been achieved, the temperatures in the combustion chamber have not risen enough to support "complete ignition and combustion" of all the available hydrocarbon molecules. This "incomplete combustion" means that some of the hydrocarbon chains are combusting "partially" or incompletely. In this stage, some of the HYDROGEN atoms break out of the compound and unite with oxygen atoms. Some of the CARBON atoms get liberated and quickly "recombine" to form both "new hydrocarbons" and "plain carbon compounds" (soot.....black). It is the resulting carbon and new carbon compounds that give the black color to the plume. This black color only last briefly in this scenario, because the temperatures inside the engine rise rapidly now, and the combustion of the fuel is near enough to complete, that the exhaust plume will become almost clear in a "good engine". But that was in a Diesel engine having combustion chamber compression pressures of more than 500 PSI. Fuel oil can be processed (combusted) very well under those conditions, but engine lube oil would require even a greater magnitude of pressures and temperatures to "burn clean". As a result, a worn out Diesel engine throws out "blue oil smoke" too (though some of that is actually "uncombusted fuel" too, when the engine is in bad condition!). In a gasoline fueled engine, the gas is highly volatile (evaporates readily). Highly volatile compounds are also "highly combustible", and will therefore "burn" in the lower compression environs of a "gasoline engine" (though not without a well timed spark to "incite ignition and propagation"). Gasoline is a complex blend of different "complex hydrocarbons". The more volatile compounds are very eager to burn and create a fast moving flame front, or "propagation wave" that moves through the combustion chamber from the spark plug "spark gap" when the plug "fires". This combustion process is not a "homogeneous" or "simultaneous" process. The highly volatiles burn and consume oxygen first, followed by the "lesser volatile compounds" as the temperatures rise (remember it takes some heat before some of these "chaste" compounds will join in). The least volatile compounds (both of the "original hydrocarbons", the "new hydrocarbons", and the resultant carbon compounds) are faced with a problem. Most of the good looking oxygen atoms have already paired up with the more promiscuous hydrogen atoms and early carbon atoms, so there "are not enough" oxygen atoms around for everybody to find a partner. Not "everybody" will locate an oxygen partner and there will be "some wallflowers" at the end. If you make the fuel/air mix too rich with fuel, there will be even more leftover wallflowers "after the dance". These "wallflowers" end up going out the exhaust in various quantities (depending on specific criteria of fuel, air, spark, temperatures, compression, and a few etceteras). It is the carbon compound "wallflowers" (soot) that give the exhaust its black color when too much fuel is present. Lube oil, (in the same analogy) does not get heated up enough to burn, but does get hot enough to vaporize and so lends the characteristic "blue oil smoke" color to the exhaust. A term that has come up in recent years (in technical speak) is "stoichiometric combustion". That term essentially means that there are "just enough" molecules (atoms) of Oxygen to combine with the Hydrogen and Carbon atoms in the hydrocarbon fuel during combustion so that there are no atoms of any of the "original" elements remaining after combustion stops. As far as one can see into the "near future" stoichiometric combustion is unlikely to be attained in commercially available power plants (engines I mean). CLASS, DISMISSED! PS, check the "choke wizard" per tomplum's suggestion.

I think part of that is because they are too lazy to update the manual. Also Briggs says THEIR synthetic multi weight is OK. Newer technology multi weight oils don't have viscosity break down like older multi weights did. Kohler specifies 10W-30 instead of a straight weight oil. You can down laod an ENGINE owners manual from the manf. website. I'd defer to that over the tractor manf. recommendations. Oil viscosity is a nominal number anyway. They run a batch. If the viscosity ranges between 26 & 34, it's packaged as a 30 weight, since they don't have 25 or 35 weight oils. One batch of 30 weight may be a noticeably different viscosity from a different batch and still be labeled as the same viscosity.