Detergent or non-detergent oil in a vintage Chevy

I’ve been using 30 wt non-detergent oil in my 28 Chevy (actual miles 34,000) and my 30 Chevy (engine rebuilt 10,000 miles ago). I’d like to know the pros and cons to continuing with non-detergent oil or switching over to detergent oil.

You may want to try a forum specific to antique Chevys. Lots of us will post well thought out opinions, but few of us will have any real experience in this area. Antique forum regulars will probably be more knowledgable.

Here is my take on non-detergent oil. I don’t even use it in my lawnmower. There were no detergent oils when your engines were manufactured. So why not use the advantages of new technology and switch to detergent oil. It will just keep your engines cleaner and possibly prolong their life.

My inclination is to agree with you, but I just don’t know enough about 1930 engines to say with confidence.

The only things I’d worry about with detergent oils are:

–you may stir up sediment and debris that can cause engine wear
–the detergent and additive package may be hard on the primitive seals and bearings used in the period.

As others mentioned, I’d ask someone that knows about these antique engines.

Use detergent, but a heavier weight such as 10W30 since these old engines had very loose tolerances.

Years ago, my dad put detergent oil in his 1949 Dodge that had a flat head 6 engine which was designed in the 1930’s. The car immediately began using oil where it had not up to this point. The detergent oil at that time (early 1950’s) also had a bad effect on engine bearings that were not designed for the detergent oil. Your Chevrolet engines have babbitt bearings and as I remember the engine is splash lubricated.
Even as late as 1963, the owner’s manual in the 1963 Studebaker V-8 that my dad purchased new called for non-detergent oil. The late Tom McCahill in his book published about 1960 titled “What You Should Know About Cars” did not care for detergent oil unless the car had hydraulic valve lifters. Now I know that oil has improved in 50 years and now even lawnmower engines call for detergent oil, but your Chevrolet engines were designed for the oils available 80 years ago.

I’ve been around old cars for a long time and I my advice would be to use the 30 wt non-detergent oil. However, ask the advice of members of old car clubs and see what they say.

I might add that I’m almost certain that your vintage Chevrolet engines do not have oil filters. Detergent oils hold the dirt particles in suspension. The oil filter will filter out the particles as the oil passes through the filter. Your engine doesn’t have a filter so I think you would be better off with the non-detergent oil where the dirt particles settle to the bottom of the oil pan.

I agree with Triedag 100%.
However, if the folks in antique Chevy forums disagree, their opinion should take precedence.

As Lt. Columbo would say, “Just one more thing”. I owned a 1947 Pontiac, a 1948 Dodge and a 1950 Chevrolet pickup truck. The engine design in these vehicles dated back to the 1930’s. I ran 30 wt non-detergent in all of them in the summertime. In the winter, I used 20W-20. I had no problems. The Pontiac and Chevrolet pickup truck did not have oil filters.

1st consult old car experts.

2nd don’t argue with success

3rd the oil change interval in these old cars wsa nothing like it is today. Detergent oils and oil filters and cleaner running engines now have oil change intervals at every 10K miles in some cars. In the old days 3,000 miles would be pushing an oil change.

I assume these are now relatively low mileage per year vehicles. Stick with the straight weight non detergent oil. I’d go with a lighter weight if you run these cars in colder winter weather and accept some oil burn off, then go to 30W in spring, summer, and fall.

Actually I think the oil change interval back then was 1,000 miles. I remember seeing an old oil can, I think it was Kendall, advertising “The 2,000 mile motor oil!”

Of course oils weren’t so great back then either…

Why do they make non-detergent 30W? Because it is so thick that it holds things in suspension without a lot of help. It will not do any harm (so I say) to switch to detergent 30W if you want to and the cost is not a factor. Do read the other posts, I don’t own a car from the 30’s so I haven’t heard anything about them.

If the engines have never been overhauled, they are full of sludge from the non-detergent oil. Switching over to high-detergent oil now will loosen up and dissolve these deposits so the detergent oil will get dirty very quickly. The '30 model with the fresh engine could be switched over with no problems…

Not only are today’s SL / SM rated oils high detergent but they are much better lubricants and you might as well take advantage of that…That old (and today’s new) non-detergent motor oil is virtually additive free. It’s just straight mineral oil…