This engine needs a thorough cleaning

August 1, 2019 | By Staff


I have a 1968 Oldsmobile that has been sorely neglected over the years and the engine is full of sludge and sediment. It is so bad that the lifters are clattering and collapsing. I have been advised that if I put a quart of automatic transmission fluid in with each oil change that it will clean it out over time. It sounds too good to be true. What’s your opinion?


That suggestion is not as nutty as it sounds, but I wouldn’t try it. I have also observed old-school mechanics putting kerosene in an engine in place of oil and running it for half an hour to clean it, but I don’t recommend that either. The transmission fluid does have a lot of detergent in it, but it is not intended for use in engines, and I don’t think it would be capable of doing much.

Kerosene is too light to provide adequate lubrication for old engine bearings, and it may dislodge grit that could score and damage them. You could break gobs of sludge loose too, and clog up the small oil galleries feeding the bearings and lifters.

Those engine cleaning shortcuts sound very tempting when you consider the alternative, but I would not trust such an approach for an engine that is as clogged up as yours is. If it were my car I would pull the engine, and then disassemble it and clean the block and other components with solvent.

In fact, if it were really dirty I would have the block hot-tanked. I would then take a rifle bore cleaning kit and clean out all of the little oil galleries in the block and crankshaft. Dip the swabs in lacquer thinner or other solvent, and swab out these orifices until the swabs come out white.

Also, while you have the engine stripped down I would check everything for wear, and overhaul re-machine or replace any worn-out parts. I would then replace all the gaskets and seals and paint the engine while it is out of the car. I realize that what I am suggesting sounds a bit over the top, but a truly dirty, neglected, sludge-filled engine will not get adequate oil pressure to the bearings and lifters, will run poorly, and will let you down sooner or later.

I know this sounds extreme, but if anyone out there in Auto Restorer Land knows of a better, less-invasive way to clean out an engine properly, please relay it to us here at tkade@luminamedia. com.

Chances are that engine could use some work inside anyway, because all that sludge is a sure indicator of a long period of neglect and problems.