Kohler engine likes to burn oil as much as gas.

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Dec 5, 2012
I have a Kohler Courage 25HP engine in my riding mower and don't have a lot good to say about it. The most recent issue is that I burned through 5 quarts of 10W30 over the course of mowing my yard. I decided to check as it had started smoking and blowing a fog of oil all over and it was a quart down after about each 15 minutes. I talked to a small engine guy about possibly rebuilding this and he said it wouldn't be worth it based on the cost of the internal parts I would probably need. He told me to just run it and keep the oil topped off and changed until it gives it up. He says that the Courage is the "economy" or "consumer" grade engine and pretty much a disposable. The Command line is what you want. This engine seems very picky about oil. I ran a Rotella T6 5W40 in it and it didn't burn much. The 10W30 that burned like mad was some Valvoline Nextgen recycled oil. I had to top it off with some Castrol Edge 10W30 I had just to finish the lawn. I didn't have a full fill of this oil but noticed consumption went down dramatically. I had used some O'Reilly full synthetic 10W30 in the past and it liked to burn that also. I am just wanting to prolong the life of this engine as long as possible and not blow fogs of oil out the exhaust while mowing. I found a Mobil 1 synthetic 15W50 and was wondering if this might be a good option. I want something that won't just squeeze past the rings anytime I hit resistance. That Valvoline Nextgen blew oil fogs anytime I hit tall grass. Obviously there is something up with the engine but certain oils seem to cause more issues than others, even in the same viscosity.
I would try sticking with the Rotella T6 you said it didnt burn much of. You might try Rotella T5 10W30 as a cheaper option. I would try that first and the go to T6 if consumption is still unacceptable. I try to avoid "Energy Conserving" oils in air cooled equipment.
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Sounds like the engine is defective or already shot. No matter what oil, a tight engine will not burn. But as suggested stick to conventional heavy weights, to reduce burn.
What does the owner's manual recommend for oil? Have you tried anything like an 'old school' straight 30 weight? Did the small engine guy have any recommendations for what oil might slow it down?
How about a big dose of Auto-Rx. A local landscaper did that trick to revive a riding mower that someone gave him because of the smoke screen it produced and the complaints of neighbors. It took running the engine a few times but it worked just find. He used double the recommended dose based on the amount of oil in the crankcase.
The engine calls for any 10W30. Basically I got it used and it was fine for a while, then the governor gave it up when it backfired and the engine ran away to max RPM. I now manually control the speed of the engine but the damage was done. It ran so hard it forced the pushrods through the rocker arms. I repaired the valvetrain but it started consuming oil after this. Yes, I do plan on trying to find another engine and would pick one up now if I could get it cheap enough. Otherwise I plan to run this old dog until it gives it up. I will probably go back to the Rotella but I may try a conventional 15W40 first. IT is strange how a different oil makes the engine burn so much more or less oil. I agree that energy conserving oils are not for air cooled equipment.
That's not just wear consumption, something (like a ring or two or the piston itself) is physically broken. With the history of overspeed and now having to ride the throttle instead of having a governor, its no surprise its trashed. Is it installed in an orientation where the shrapnel is going to go through your vital organs when (not if) it grenades? :-p Actually I'm only half kidding.
Originally Posted By: cwatkin
The most recent issue is that I burned through 5 quarts of 10W30 over the course of mowing my yard.
That's $15 or more of oil, per mow? That engine is highly worn and has internal damage. Or the other option is that it is so grossly overfilled with oil that it has no choice but to burn it off. How much oil does it have in it altogether? Are you using the dipstick? These engines hold less than 2 quarts of oil. In high school shop class, a kid filled an engine with like 20 or 30 quarts of oil, because "He looked down into the hole and saw metal and thought it should be covered in oil".
I think the overspeed is what started this. They use plastic governor gears and those tend to shear off causing that to happen. My mower guy says he sees more of these engines trashed because of poor workmanship or low quality materials and doesn't see it as worth fixing/rebuilding. I agree that there is something wrong with this engine but certain oils don't burn nearly as much as others which I find interesting. This engine obviously doesn't like Valvoline Nextgen or O'REilly brand full synthetic 10W30. The Nextgen was the Maxlife variety. I still had the container in my trash and looked. This engine is definitely very oil sensitive. I can go a whole mowing on Castrol Edge 10W30 or Rotella T6 5W40 and only be a little low after I am done. The others just blew out as a fog at a rate of about 1 quart every 15 minutes. I seem to recall the engine holding 2.5-3 quarts with an oversized filter. Yes, I do use the dipstick. I fill it up to a little above full, start the engine and let it run a few seconds to fill up the filter, and then add some more to top if off. I then run it like 5 minutes mowing and shut it off and double check again. I am not overfilling but figure the extra reserve capacity of a larger filter is worth having with this issue. I have one of those Geo Metros and the stock filter for this is the same exact one specified for my mower (don't laugh). Since these only hold like 3.5 quarts, I get the oversized filter and it will hold 4.25 quarts or so before hitting the full mark on the stick. I use the same filter in this mower.
The time it overspeeded was when I had it idling and went inside the house to get some water. It backfired and took off. I came out as the engine sounded like it was going to take off. It popped and came to a stop and wouldn't start. I could tell something was up with the compression so either figured something was up with the valve train or the engine had blown. I removed the valve covers and found the pushrod through the rocker arm on one of each of the valves. I replaced those and the ones I didn't replace went soon after. I replaced those and no more issues with that problem. Lash is set to spec which I think was .004. Obviously if it had gone fast enough to hammer pushrods right through the rocker arm, it probably did some other damage. It ran fast for a bit after I fixed that, not realizing exactly what had happened. It was at night and the oil fog blowing out of the muffler was igniting in a big mass of flames. I have a video of this if those can be posted here.
At this rate I would start using used oil especially if you are looking for a new engine. No sense in wasting money on something that burns 1 quart every 15 mins. Run it until it dies and have some fun. Keep it topped off and you should be golden. Just out of curiosity, how much did the T6 slow down consumption.
Just go to harbor freight and pick up the biggest engine they sell. You may be down a bit on power but at least it won't be costing you $15/mow just in oil.
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