Re: Detergent vs. Non-Detergent Oil:

Posted by H. L. Chauvin on Sep. 15, 1998 at 22:46:33

In Reply to: Detergent vs. Non-Detergent Oil:Here we go again!
posted by Gordon Biggar on Sep. 15, 1998 at 19:44:35

: This debate seems to crop up every six months -- like clockwork.The last reference that I see on the Board is dated August 12th, but it relates to STP being used with non-detergent oil.
: The reason that I raise the issue is that this afternoon I was chatting (by telephone) with John (son of Pete, the owner)of Pete's Auto Machine in Albuquerque.They recently babbitted my block, and they have done many insert bearing jobs for "A" enthusiasts throughout the country.John stated unequivocably that non-detergent oil should be used with babbitted engines.The reasoning, says he, is that the detergents in detergent oils create a chemical reaction with the babbitt, which situation is particularly harmful for those cars that are not driven frequently (e.g., that sit over the winter).
: Are there any (would-be) chemists out there who would like to comment on this subject?If I can round up enough diverse opinions, I will try to contact the technical folks at Shell Oil here in Houston for their thoughts.
: Thanks for any and all inputs.
: Regards,
: Gordon Biggar
Hi Gordon,
One humble opinion, one humble experience.
Thoroughly cleaned out a free, Model A rebuilt engine given to me in late 1950's which had new babbit and burnt valves. Owner had incorrectly mixed and installed valves.Valves were resurfaced, lapped, and switched to correct INT & EXH valve positions. Filled engine with 30 weight detergent oil and drove car with same engine for 12 years, changing oil at 500 mile intervals. Later stored car without changing detergent oil for 24 years.Recently had engine checked:babbit is fine, no shims to remove;pistons, rings, & oil pan free from sludge, clean, and engine interior looked like new -- advised to install new rings after honing -- not enough wear for cylinder re-bore.Had always used "Amoco" lead free white gas with 4 oz. of top cylinder lubricant, (Marvel Mystery Oil, etc.), per full tank, and always used detergent oil.
My opinion is to always use detergent oil for rebuilt cleaned engines and that top cylinder lubricant helps to cut down on wear of upper part of cylinder, valve stems, and valve guides.Unleaded gas greatly reduces carbon in combustion chamber and reduces carbon fouled plugs.
If an engine was running on non-detergent oil, clean out oil pan and valve chamber prior to switching to detergent oil -- old engine sludge could plug screen on oil pump and reduce flow of oil causing premature engine wear.
Let us know what you find.
Best wishes,
H. L. Chauvin