Oil seeping from under rear of head

[Old Mose]

My 77 XS400 has a minor oil seep from between the rear of the cylinder and the head. It never even drips, you can just see it gets black and I put a rag under it and clean it off with brake cleaner about once a month. Is there anything that should, could or can be done about this. I pretty much ride it everyday when it's not extremly hot or cold because I enjoy it and it uses a lot less gas than my air conditioned pickup. Any kind of repair beyond minor will need to wait until the dead of winter, if possible! THANKS

 

[Lou Ranger]

I am not an expert, but I have had some experience. Based on that, I would say you have nothing to worry about.
Last year I owned a Honda 450 for just over a month and put over 2,000 kms on it. Then a friend bought it and he has put many more kms on it over the year since. From the day I got it there was some oil seepage - not enough to drip, but enough to wipe every day that I rode it. In spite of that, I didn't need to add oil to keep the level above the fill line all month.
My friend reports that the seepage has gotten worse and that he intends to repair it next winter, however, he continues to ride and simply checks the level every day and now adds a small amount occasionally.
Sounds like your leak isn't even close to where mine was right at the beginning.

One cautionary note which I was warned about -don't know if it's true though, but worth considering. I was warned not to switch to a more expensive synthetic oil rated for wet clutches. The old mechanic said that part of what seals the pieces of an old engine together is some residue form old oil that has been through the engine over the years. He claimed that some of this was likely contributing to minimizing the amount of gasket seepage. Based on his experience, he said switching to a synthetic can start dissolving some of old oil gunk and increase the seepage.

 

[Old Mose]

Thanks for the advice. As you said, mine isn't even a leak. Over a month of riding about 10 miles total everyday, the oil level never changes, just turns the fins at the top of the cylinder black. I do an oil change every six months and haven't had to add any oil between changes! On the other note, I'm a retired auto mechanic and I would tell you just what the old mechanic told you. If it didn't start out with synthetic, you are only asking for trouble. DO NOT CHANGE TO SYNTHETIC OIL!

 

[Lou Ranger]

... I'm a retired auto mechanic and I would tell you just what the old mechanic told you ...

That's good to know. Sometimes we neophytes can't help wonder if old mechanics aren't just having a little harmless fun at our expense when they regale us with ancient wisdom or stories from the past. When the story or the ancient wisdom actually makes some sense though, I always hope not.

Wouldn't that make a great thread on the Forum?
Luddites, neophytes, rubes and newbies could post stories they have been told by ancient mechanics and riders.
Then we could vote: 'truth', or 'having us on'.

 

[xschris]

I have been running a synth blend in my 79 for more than 10 yrs (ran dino for 5yrs. before that) with no issues. The motor has 32k on it now and still runs just fine. Also run the same in my 80 that I have had for three. I also use lucas full synth in both (10%). I think a lot of it is people have 30+ year old gaskets and seals that are just worn out and should be replaced. My 79 has new gaskets and seals but the 80 has the original ones.