Help on choosing the correct engine oil

[1929Chrysler]

I recently had my straight six engine completly overhauled with everything meticulously cleaned in the process. I wanted to give it an oil change this weekend and my mechanic told me to use 10W 30 Detergent oil as a "break in" oil. I went to the local NAPA and they had no idea what I was talking about. My mechanic is out of town for the week so I can't ask him. Does the guy at NAPA not know what he's talking about or am I not communicating properly?

Can the gurus out there also give their opinions to me about the proper oil for my purpose?

Thanks in advance.

Dan Pajestka

1929 Chrysler

[FomocoService]

The big thing with oil is as old as the hobby itself. Oil & whether to add lead or not to the fuel are always a hot topic.

There's really no wrong oil to use - aside from synthetic as a 'break-in' oil don't use it initially.

Most oils are detergent unless they state 'non-detergent' on the label.

You probably threw the guy off when you said 'break-in oil'. I'd just pick out your favorite brand of 10W30 and go with it.

[Guest]

When I rebuilt my engine I used straight #5 weight oil as break in oil. I change my oil every three months (about three thousand miles). When I had 50,000 miles on the engine I changed to #10 weight and used that until last year (at 390,000 miles) I went to #20 oil. I had tried multi grade oils in the past and was never satisfied with how the oil pressure changed during the day when we were travelling five or six hundred miles with only stops for gas and food.

I worked for GM and an engineer told me that the thin oil lubricates a good as thick oil and circulates faster. Therefore you should always use the tinnest oil as a break in oil and only change up when/if you find your oil pressure dropping.

I don't know if this theory is right or not but It's what I have done for 47 years in all my cars (one with 481,000 miles and one with 250,000 miles {the other 26 were just throw away cars}).

[A by the sea]

The mysteries of oil, a quick overview.

This has been a tough topic for years. In the most recent Model A News there is an article on the differences of oils. They did not say which is best, but they pointed out the differences.

The proper thing to ask is what additives are in the oil.

Some oils, like many single weights oils, are none detergent and may lack any additives.

Additives will prevent the formation of nasty chemicals, help keep oil on the wear surfaces, and other positive benefits. Detergents are to keep microscopic dirt in suspension and are pretty important even in cars with filters.

Multi weight oils are good because they are thin for starting and thicken as they warm.

An engine that gets used a little and then put away for a while will tend to build up moisture. The moisture will combine with sulfur by products that end up in the oil. Then you get sulfuric acid that will eat at your engine.

Oils designed for diesel engines (compression ignition) will have more additives to combat acid build up and other bad chemicals.

While there is no research to properly prove which oil works best in an old engine. It is pretty obvious that you want additives that will prevent bad chemical build up. You generally want to have multi weight oils and you want detergents.

For most antique cars, you just need to pick a quality oil and change it at a reasonable period and you should be fine.

[Guest De Soto Frank]

Dan,

If you've got a fresh, squeaky-clean engine, use detergent oils to keep it that way.

If the vehicle does NOT have an oil filter, it has been suggested that NON-detergent oil is better, as it allows grit and impurities to settle to the bottom of the sump and stay there (forming sludge), rather than being kept in suspension by a detergent oil and continually being circulated around the engine...

Any major brand of 10W-30 oil should be okay, if that's the weight your mechanic recommended.

To the best of my knowledge, all readily available multi-weight oils are detergent; in my thirty-plus years of working around cars & trucks I have never seen a non-detergent multi-weight.

Non-detergent oils will be plainly-marked as such on the lable.

Your NAPA man is probably too young to have had a chance to encounter Non-detergent oils, therefore, when you asked for "detergent oil", it threw him for a loop...

Good luck with your '29 !

[Packard enthus.]

the important thing to remember, is that the descriptions of motor oil are like any other product subject to mass-merchandising advertising campaigns...UTTER NONSENCE.

"Detergent" oil ? Of course there is no such thing. The term "detergent" was selected by advertising clowns who recognized most people do not know, and do not want to be bothered with technical explanations. In the late 1940's, oil engineers came up with a formula by which the oil molecules no longer "link up" to form sludge at normal operating temps. Of course "detergent" oils do NOT have the effect of soap; can NOT dissolve ANYTHING. They simply wont ADD to EXISTING sludge.

The ONLY reason for recommeding a so called "NON detergent" - meaning an oil that WILL produce sludge, is if you have a friend or family in the engine over-haul business who needs some more work. In the days BEFORE the oil engineers came up with the so called "detergent" ( or, again, oil that will not form sludge) engines typically ran about 40-60,000 mi. before needing a complete rebuild. Once we had "non sludging" (if you like the silly and inaccurate term "detergent" use it) engine life increased dramatically.

The second nonsence term is "mutli grade" oil. Of COURSE what we CALL "single grade" oil has multiple grades, depending on the temp. Of course MULTI grade oil stays a predictible viscosity at all operating temps. It will flow when very cold, and not thin out when it gets very hot.

The big advantage of these so called "multi grade" oils is that they continue to flow to vital parts at low temps when you first start up on a cold morning, and do not thin out at extreme temps. Of course so called "single grade" oils do not have to meet ANY viscosity standard EXCEPT at 210 degrees.

Thus if you are in the engine repair business, or have a relative who is so employed and needs more work, by all means recommend so called "single grade" oils. When the car is cold, they are so thick, they cannot provide good lubrication, so you get destructive wear.

In the mid-1950's, I went thru the very sludged up engine on my '38 Packard V-12. At the time, to try and help my buddies understand that the new "detergent" oils can not remove sludge, I left a couple of areas of sludge on some of the crank-throws, and some places on the crank-shaft bearing webbs. Of course, some 150,000 mi. later, on a regular "diet" of 10-30W oil (dosnt matter what brand..they all have to meet the same SAE / ASTM standards) that "test" sludge is still there - the rest of the engine remains clean and reliable.

The important thing to remember, is that much advertising these days, is geared to try and get into the "head" of the ignorant. Try and be smart, and figure out what is REALLY going on.

[Mike Cullen]

Outstanding explanation Peter. I recently stripped a mid 30s flathead V8 that had not been run for over 50 years. I forgot just how nasty and sludged an engine can be. I haven't seen an engine that sludged up since the late 60s when I first started turning wrenches. (btw, it was a wreck, the odometer showed less than 50,000 miles, and it had been rebuilt already, .030" over!) How soon we forget, I've been averaging 200-300K miles on today's cars without anything except normal maintanence.

[Sweepspear]

The real problem with using today's oils in our older cars is the lack of zinc content.

Many are wiping out thier cam lobes especially during break in.

The consensus is to use diesel rated oil along with an additive like GM EOS.

There is a good discussion on the topic over at V8 Buick.com.

(Scroll down into the thread to get to the zinc issue)

http://www.v8buick.com/showthread.php?t=113679

[Guest De Soto Frank]

My understanding of a "detergent" is that it is a cleaning agent that keeps "dirt" in suspension in whatever the "vehicle" is (laundry water, dish-water, engine oil) and prevents it ( the dirt) from settling-out.

Thus, the "dirt" goes away with the rinse cycle or at each oil change.

According to any of the API bulletins I've read, that is what "detergent oil" does.

Or is this simply propaganda generated by a puppet organization(American Petroleum Institute) of Big Oil Interests ?

The only recoomendation I've seen consistently today, advocating the use of ND oils in automotive applications is for things like oil-lite bushings that are adversely affected by Detergent oils, and in the crankcase of engines that do NOT have oil filters.

I believe that Packards all had oil filters by '38 ?

Can't say that I know better than the next guy; I've dumped modern detergent oil in my pre-1960 cars and trucks for as long as I've been driving them; but they've also all been beaters that are due for rebuild anyway.

If Dan's '29 Chrysler six is still squeaky-clean from its re-build, then he shouldn't have any worries about modern detergent oil breaking-loose 70 years worth of sludge.

( I wonder what the brass folks who do a lot of touring use for oil ...)