I recently began to make iso oil myself and have been very pleased with the results, especially considering I used to throw the stuff away that I make the oil from now...I'm old school and can remember my friends making it some 30+ years ago, (with those big old light bulb percolators you ordered from High Times) but I hadn't smoked any for many, many years. The first few tries came out nasty, and green, but I found if you freeze everything before hand it comes out very nice, lite brown and very hashy tasting. I used less than an 8th of trimmings and made a batch the other day and took it to play pool with 7 bros...we all stayed blazed all evening from the small amount of oil I made (maybe a gram)...we just put a drop on top of a bowl and smoked it, and repeated as necessary until wasted, which didn't take long! I've tried all the ways to make it except the expensive devices that recover the solvent, (Iso alcohol is cheap, so why recover it?) and the iso-evaporation extraction is by far the easiest, with good results. And yes, oil REALLY expands in your lungs, so take baby hits until you figure how hard to hit it...mine is very mild, sweet tasting and potent if you don't over-hit it...if you do over-hit it, it will nearly kill your lungs!

BTW, I don't soak it for 48 hours, I just vigorously shake the mix for 5 mins and then strain and filter...your getting a lot of waxy components from soaking too long if it's tarry tasting ...the stuff you want in your oil dissolves pretty fast, so no need to soak the solution for extended periods. You would be better off doing a second or third quick (5 mins) wash of what you have rather than extended soaking times imo.