Nasty Oil

I am back on a 75 CR250 after it was sold to a friend 35 years ago and then re-acquired by me. My friend let it set for decades at a time - only buying a new air filter and firing it up once every 15 years or so. I have got the bugs out of it (literally) and have started racing Enduros in the EVO class. Only thing is that i change the oil about every 3 hours running time and it is always gray and sludgy. I use Castol GTX 20/50 - which is what i think I used back in the 80s. I seem to remember doing oil changes back then and the oil coming out fairly clean after use. I kind of expected nasty oil the first few changes, but this is about the 5th and it is still quite nasty. The bike runs and shifts like new - just concerned that something is going on. Any thoughts or insights?

Have you checked the clutch yet by removing the cover and plates to inspect them and clean all the grooves out on the plates and gently rub the metal plates with some 400 wet sand paper while your in there. I would try spraying some brake cleaner as you have the cover off and take the drain plug out and try to spray all the crap out. As you spray gently move the kicker by hand rotating the trans. in all positions that should get her cleaned up pretty good. I like brake cleaner because it drys very fast and it is under pressure and it comes with a straw too, Use 1 can and let it air dry real good maybe even blow it with the air compressor before you oil up again, good luck let us know the results.

Thanks! I hadn't thought of it being clutch plate residue - was thinking something worse. I'll give your remedy a try this week and post the results.

This is one thing that got to me with the 390. I would do an oil change, then fire the bike up. It would run for 5 minutes. Cup of coffee, and then check the level. It was as black as it was before I started.
After thinking about it, I replaced the alloy plain clutch plates with steel ones. RESULT ! Clean oil and a way better clutch.

Good info. Where did you pick up the steel plates, Grouty?

You can likely get them from www.husqvarna-parts.com. If you do not see them listed, send Phillip an email. There is so much he has that is not listed in his website

Yes, I got mine from Phillip.