Cleaning oil/sludge out of coolant recovery tank

My Challenge Riviera's coolant overflow/recovery tank is a complete mess- either it at some point had a problem with oil in the coolant, somebody REALLY stupid thought it was where you added oil, or when it was converted from Dexcool to universal it turned into oily sludge- regardless, the inside of the recovery tank is coated in oily gunk.

What's the best way to clean this crap out? It's too heavy to just blast off with a hose, not to mention there's a limited amount of the inside of the tank that I could actually hit with a stream from the hose. Thanks!

find a better one at the JY? Power washer?

Plug it/cap it, fill it 1/3rd full with a strong degreaser, and shake-shake-shake...shake-shake-shake...shake your booty.

Replace with new if still available.

That's what we do at work... we've tried all sorts of degreasers, agitation until your arms are numb, etc. If you can't physically scrub it out, you're not going to clean it all out.

The oil is from a previous failed intake gasket. Unless it is from a current failed intake gasket. Oil naturally migrates out to the overflow tank.

Alternatively, since this is a Challenge car, just ignore it. It looks ugly but the oil isn't going to go back into the main cooling system.

I'd try Awesome.

Hand full or two of nuts and bolts and dawn dish soap and some hot watter and shake it a bunch

petegossett wrote: Plug it/cap it, fill it 1/3rd full with a strong degreaser, and shake-shake-shake...shake-shake-shake...shake your booty.

perform steps 1 through 4 as above with water, soap or degreaser and rock salt. Works wonders.

Thanks for the suggestions! I'd not thought of putting something (like bolts/rock salt) in to help with abrasion/agitation. And for some reason didn't think of dish soap.

I'd prefer just cleaning out the current one to replacing it, both for the fact that I want as much budget as possible for power/handling and for the fact that I'm not wholly certain that anything other than another Riv's coolant bottle would fit and they're not the MOST common car in junkyards.