Detergent or Non Detergent Oil

[tangaroa3]

Yesterday I was at the store to get oil for my oil change. I've run straight 30 weight oil for years...but for the life of me I could not recall if I used detergent or non detergent. I guessed non detergent (basic old engine) , bought it, changed the oil, and today I'm reading the polls on line here saying to use high detergent.
I'm guessing there is no harm in having clean NON DETERGENT oil in there for a season, but are there any issues I should be aware of? Lastly, what is the real world reason for recommending HIGH DETERGENT oil for these old beasties?

[joe_db]

Where would you even FIND that? Sounds like basically crude oil in a bottle.
I use Shell Rotella 15W-40 with detergent with good results

[Dave Neptune]

Non detergent oils are primarily for "break in" purposes. Once broke in a detergent oil is used (since available in the 50's) as it keeps the engine clear of deposits which could break loose and cause havoc.

Dave Neptune