Re: Engine oil

Posted by Dave Kenney On 2008/2/7 19:25:52

Tim, Welcome to the forum and thanks for your input. I am interested in what you have to contribute since you do seem to have some experience with Packards.
The owners manual for my 47 Super Clipper with the 356 CID engine states that oil should be changed at 1000 mile intervals. Are you suggesting that if I use detergent oil I should change the oil at 500mile intervals? My knowledge of oil is very limited as I am not a chemical engineer but I have been of the opinion that the word "detergent" in reference to engine oil, is a misnomer since it doesn't mean it cleans the engine but rather it has additives which trap contaminants and keep them from harming the engine and also controls the development of sludge. How can this be harmful when compared to non-detergent oil if oil is changed at the specified 1000 mile interval? I also realize that the bypass oil filter system are not as efficient as the modern flow through types.
One of the first things I did when I bought my Packard was to remove the oil pan and clean out a thick layer of sludge. After 4 years of summer season driving I removed the pan again and found only a thin layer of sludge which I suspect was just material that had been lurking in the passage ways and lifter gallery since the first cleaning of the pan. Obviously to me the modern 15W40 Diesel oil that I have been using has helped control sludge build up and is superior than the sludge forming original oils used in the car for it's first 50 years of life. I use the diesel oil because the 356 engine is a dirty engine by modern standards and more particulate matter is deposited into the oil. My understanding as a layman is that diesel grade oil has more additives to trap particulate material than do gasoline engine oils. Help me if I am making a wrong assumption but please also justify your argument with facts or at least personal anecdotal experience.
As to driving flat out I am in agreement that these old cars with their long strokes and heavy pistons are suseptible to engine failure if pushed beyond designed rpm limits; so is any engine for that matter.
I must admit that I drive my Packard sedately to conserve gas and the 60 year old engine but once on the highway and with overdrive engaged it seems to cruise comfortable at speeds of 60-65mph. Thanks for listening!
BTW do you own a Packard?