Gunky fuel tanks--Tried something new. Got some Berrymans B-12 Chem-tool. On sale at O Rileys. Poulan 361 fuel tank--So gunked up fuel filter was stuck to bottom of tank.Fill and shook then let it set over night--Shook through out a Sat. Got really clean-filter out--Pour back into can and save. Will eat paint off-and rubber-did not hurt plastic cap . also had a husky 268 tank bad shape-- filled with asphalt release liquid--I work for a road building-paving co. Did a great job steamed out with steam jenny---Total time 5 minutes--If you know any one in paving biz--A cup is all you need. I like that old sand cast poulan above--Gear reduction and a bow-- David