KubotA G1800 with about 900 hours. So I have, what appears to be a small oil leak, where the inlet manifold attaches to the cylinder head. Oozing out between where the inlet manifold attaches to the cylinder head. If could be a bad inlet manifold gasket, but I can't imagine oil being in that area of the cylinder head. Do I have a crack in the cylinder head that is allowing oil to that area? I have attached a photo of the leak area of interest.
For help with the picture, the oil leak is just below the middle injector a smidge to the right. Right where the inlet manifold attaches to the cylinder head.
So i solved the leak issue. Since I got the G1800 lawn tractor with 400 hours I have been using conventional oil. The G1800 had about 930 hours a couple months ago and for the first time I put Rotella T6 synthetic oil when I changed the oil. Shortly after that I had oil leaking out the top of the engine in three different places. I replaced the valve cover seal and oil cap seal and stopped those, but stil have the leak in the picture above. So when I realized starting to use synthetic oil the problem occured, I read online a bunch. The majority of the time, folks change to synthetic without issue on 'older engines'. But a few develop oil leaks when changing to synthetic with a older engine. Apparently my engine is in the 'one of the few' category.
I changed oil last week and used convention Rotella straight 30 weight oil. After mowing twice the one remaining leak is gone and the top of the engine is oil-less. I would have not thought that switching to synthetic caused the problem, but can't find any other reason for the fix.
