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Motor oil for a '23


Scott S
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The type of motor oil depends on how you intend to use the car.

If you aren't going to drive it much and do not intend to take the engine apart for any sort of repairs, then use non-detergent oil and change it often. (Every 500 miles or once a year).

However, I would strongly recommend that you drop the oil pan and clean out all of the accumulated sludge that you possibly can so as to get it out of the circulatory system. While in there, pull out the pistons to inspect the connecting rod bearings and, if at all possible, check the main bearings as well. The reason is that old original babbitt, which this car has, becomes brittle with age. You might find large chunks missing or visible cracks in the bearings. This is bad, for obvious reasons. If one of your bearings disintegrates while driving, you will ruin the crankshaft journal, which will be an expensive fix. Better to check these things now, or for a good winter project, and then next spring you can drive in confidence.

Several businesses around the country will rebabbitt your engine parts for you, or rebuild the whole engine if you have the money and lack the confidence. A full engine rebuild runs about $2000 a cylinder, but just new babbitt costs about $50 a bearing (your milage may vary).

Once apart (as long as you've gone this far) have the cylinders rebored and install new pistons. You'll be alot happier if you intend to drive the car very much.

And when you are done, with a nice clean engine, you can use detergent oil --- Shell Rotella 15W-40 is commonly recommended, but everyone has their own favorites. Just remember that anything on the market today is far, far better than what was available in the 1920's (or even thirty years ago).

--Scott

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Forget the "non-detergent" oil. The only thing with that product is that it does not hold combustion byproducts in suspension, so a car that is not driven frequently will "sludge" that is, the crud settles out so that when you do change your oil, much of it will remain in the engine, settling everywhere. I had forgotten how nasty an engine using "non-detergent" oil will get. I recently tore down a 37 V8 that hadn't been run in over 50 years, it was a wreck with less than 40K miles. There was sludge of 1/2" or more everywhere, blocked drains, etc. I can't see opening up the engine as frequently as was common back then just to clean sludge out. The oil you drain will settle out clear if you let it sit undisturbed for a while. Standard oils of today will keep the crud in suspension, but will not "clean" or dissolve any deposits already there, when you change the oil, out goes the crud. With our antique cars we change our oil frequently, and the oil we have is so much better than the cars originally used, you will likely not have an oil related failure. Personally, I change my oil every 1000 miles or so, but it is a pressurized system with a partial flow filter. If you have an early splash only non-filtered system, you may want to change at 500 miles or so, just to be sure you don't have any big chunks floating around in there. If you are worried about the lower levels of ZDDP in the latest SM rated oils add the GM EOS break-in additive when you change. also, if your antique calls for SAE 30, modern 10W-30 is fine. Yesterday's SAE 30 oil is actually about equal to SAE-20 of today. You can go heavier of course in the case of worn, sloppy engines with excessive bearing clearance.

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  • 3 weeks later...

Scott,

Many disagree on this subject, but I use non-detergent oil in all my cars. In my opinion, (and it is just an opinion), cars without filters (or once through oiling systems like my 13 Buick) have no need for detergent oils.

I agree with other posts on this forum; that the cheapest non-detergent oil you can buy today is much better than the oils these cars used when they were new.

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There is no reason to use non detergent oil in an engine without oil filter. It is correct that non detergent oil will not suspend all the sot particles but when engine is running a lot of these particles are pasing through the bearings. In non detergent oil these sot particles will be large and may harm your berings. If you run an engine with non detergent oil and has an oil filter, you will see that most of the sot particles end up in the oil filter. With detergent oil, on the other side, the suspeded particles are so small that they pass through the oil filter. These particles are so small that they are harmless to bearings.

Jan

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