When I woke my 38 up from it's extended slumber, I drained the existing oil and refilled with detergent 10w30 plus a quart of kerosene. I let it run for 15-20 minutes at a slightly high idle to get it warmed up, drained the oil and refilled without the kerosene. All was well. Others may do it differently. I'm sure we'll get other's experiences to draw from.

I would start with dropping the oil pan and clean the crud out, if nothing looks bad and no bearing in the pan go ahead and get it running.

@tiny I’ve heard people say to stay away from oil with detergent, because it might knock some crud loose, and do damage to the engine. do you think that’s true?

Thank you for your response!

@dennis-christianson Thank you for replying! I did drop the pan, cleaned any crud out, check the oil pump, and put the pan back on. I did manage to start it up for two or three minutes, but then I started worrying about oil circulation. With the valve cover off, are you able to see whether or not oil is circulating?

Thank you!

When you had the oil pan off, did you clean crud out of the oil reservoirs that collect the oil mist (since it's a splash oil system) and feed oil to the camshaft bearings and crankshaft main bearings? You'd have to use a small inspection mirror to see these reservoirs above each bearing.

When the engine was running, did you have the rocker cover off and did you see oil dripping from the rocker arms?  If there was oil getting there, then the oil lines to the rocker arms are clear.

Cheers, Dean

Posted by: @john-cunningham-2

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@tiny I’ve heard people say to stay away from oil with detergent, because it might knock some crud loose, and do damage to the engine. do you think that’s true?

Thank you for your response!

I'm not a chemical engineer but my experience has been the opposite. I've read that the 'detergents' in modern oils don't "clean" but help hold contaminants in suspension to prevent the build up non detergent oils cause. The contaminants are then flushed out when the oil is changed. They are not solvents. The kerosene I used would be far more likely to break build up loose than any oil and it didn't. Ask oil questions and you'll get many different answers and opinions. My experience is that non detergent is far more dangerous than detergent oil because it allows contaminants to build up.

@tiny Thanks, all good information!

@john-cunningham-2 

Listen to Tiny.  He knows of what he speaks.  👍. 🙂

NEVER use a non-detergent oil in an old Chevy.

I am not a Chemical Engineer either but am a retired Research Chemist that worked in automotive R & D for many years. I can assure you that the detergents in modern oil will NOT dissolve the crud in the oil pan. As written above the detergents added to attract small particles in the circulating and make the resultant globs large enough to be removed by a filter or drop to the bottom of the pan to be flushed out the next oil change. 

Caution: You will read many tales from "Experts" and others that claim to know of what they write. There are also many companies selling "miracle" or "necessary" products to the automotive industry that are claimed to be necessary or beneficial. Hopefully most are not too detrimental. 

@chip Chip, I've had great advice from you in the past, and I trust you 100%. Detergent oil it is. My only concern would be that my ‘30 has no oil filter. 

None of my older Chevrolets have an oil filter and I don't plan to install one. The amount of dirt, dust and other small items that might be captured by a filter is essentially NOTHING. Larger particles will not be picked up by the oil pump so won't go to a filter even if one is installed. So the most economical is change the oil once a year is driven over hundreds of miles. Mostly what will be removed will be water, acidic gasses from combustion that are more of a hazard to the engine than any particles from wear or the environment, These are not modern vehicles or driven like them so don't need all the accessories that are hung on modern engines.