I was thinking lately about changing the oil in an old Chevy, back when I was a kid. In those days the older cars used non-detergent oil. I don’t even think you can buy that anymore. Sometime in the 60’s, I guess, they switched over to oil with detergents added to it so your engine would stay clean inside. Sort of a self-cleaning deal. Anyway, if you changed the oil on your old ’49 Chevy 216 cubic inch straight six, and you put detergent oil in it, after a short time of driving it you’d start to hear the tappets clicking real loud. That’s because the oil feeder tube that sent oil up to them would get clogged up with all the crud that was being cleaned off the inside of the engine by the detergent oil.
So, normally you’d just put non-detergent oil in it and forget about it. But if you really wanted to change an old engine over to detergent oil, which was a good thing, I guess, well then you’d have to change your oil a few times, and here’s how you’d do it:
First, you had to buy enough oil for 3 oil changes, all at once. And you’d have to buy 3 filters, too. Along with that, you’d need a couple of quarts of diesel fuel. Some people even used kerosene, although I never did.
The first oil change involved (in the case of the Chevy six) putting in 4 quarts of regular detergent 30 weight oil, and adding a quart of diesel fuel to it (or kerosene if you were brave), and changing the oil filter. If you couldn’t find diesel fuel or kerosene, a quart of automatic transmission fluid would work. You’d fire up the car and drive it around for a half hour or so…maybe go to the store and back, or something. Just enough to warm the engine up and let the diesel do its work. Then you’d come home and change the oil again while the engine was still warm, this time just putting in 5 quarts of regular 30 weight detergent oil, and changing the filter again. Sometimes it was amazing how much crud came out of the engine, just in that first half hour of running it. If it was exceptionally cruddy (and most of them were…), you’d use 4 quarts of oil and the quart of diesel again, and run the car for another half hour or so. Then you’d change the oil and filter yet again, this time with just 5 quarts of detergent oil.
So, now you had detergent oil in your old engine, but it still wasn’t completely clean yet. You’d drive the car around for a week or so, until you had the time to change the oil again. Same deal. You’d drain the old oil while the engine was still warm and the oil was thinner and would carry out more of the crud. Then you’d put in 5 more quarts of detergent oil and another new oil filter. At this point, I would just resume normal oil changes, although it wouldn’t have hurt to do another oil change a week later.
It seems so far away now, the times when we used to buy reclaimed oil from the gas station, and have to ask if it was detergent or non-detergent. The reclaimed oil was just reused oil from oil changes the gas station would do on cars, and then they’d pour the old oil into a drum, through a filter of sorts. It was really cheap, I think about 5 or 10 cents a quart, compared with new oil that was probably 30 cents a quart.
Gasoline was about 19 cents a gallon then. We could fill up an old Ford woody with gas for about 2 bucks, fill up the back with surfboards, and head to the beach.