The books show a capacity of 9.9 quarts. Last Friday, I did the 50 hour service on mine. After draining from both drain plugs and changing the filter, I added 9 quarts and about a fourth of another quart bottle and let it sit for about 15 minutes while doing other items. When the oil level was checked, it was way too high. I cranked it and let it idle for a few minutes, then shut it off, let it cool and checked it again. Got the same reading as before. I ended up draining about a quart back out. I then went and made notes in the manuals to only add 8 quarts before checking it. Is this what you are suspecting?