Modern Oil Break Down?

[aero3113]

How many miles do you think it takes modern oil to break down in a flathead?

[55 Fargo]

How many miles do you think it takes modern oil to break down in a flathead?

I think you would have to look at and consider some variables in the engine itself.

Full flow oil filter,or By-pass

PCV set-up, or road draft tube style

engine rebult and pronounced clean internally, or unrebuilt, and not so clean internally.

engine operation temps

city or highway operation

conventinal versus synthetic oil

Oil in a full flow set-up is recommended to be changed at 5000 miles, based on 1940s oil

Oil in by-pass set-up, every 3000 miles in temps above 32 f, filter every 6 or 8 k, can't remember now.

How often is engine and oil used allowed to sit between operation, is the car stored for long periods of time.

My regime with an unrebuilt, but fairly clean engine, with a totally stock engine is 2 to 3 k, and an oil filter each time, even though it is a by-pass type.

I would guess if the car was driven civily, and on a regualr basis, 5 k would probably still result in good oil.

I have no empirical data to support this.

I do venture to guess, that modern oil, the way we drive our old girls, is whole lot better than 1940 and 50s oil and everyday hard use.

I think these flat head 6s were used a lot in Chicago and New York cabbies for many years, and with plenty of miles no doubt between oil changes.

[mrspeedyt]

these modern oils don't break down...it just gets dirty. i've been changing mine at about 1000 miles in my '41. it's really dark at that point. i now don't change the filter every oil change... maybe 5000 miles or so. haven't seen any difference since finding the car in 1975.

[desoto1939]

these modern oils don't break down...it just gets dirty. i've been changing mine at about 1000 miles in my '41. it's really dark at that point. i now don't change the filter every oil change... maybe 5000 miles or so. haven't seen any difference since finding the car in 1975.

You stated that you are changing the oil every 1000 miles because it looks dirty and dark. Are you using a mulit weight oil like 10W30 10W40. If so this is why the oil looks dirty. The 10Wx has a detergent inthe oil that helps to clean the engine and this oil will get dark very quickly. The oil has not lost its vescosity or ability to lubercate your car. The cars of today and the oils of day can go 3000-5000 miles before an oil change. I think you are changin ghte oil way to soon. Do you also have a filter and I am assuming the bypass style. If you are not running the car in an enviornment that has alot of dust like riding on dirt roads all the time then I would at least go very 3000K with the filter chnage also.

Rich Hartung

Desoto1939@aol.com

[TodFitch]

Isn't that like putting on a new pair of chino's and not changing your Skivvie's:)

Bypass filter can be run until it is clogged, so you don't need to replace it every oil change.

Full flow filter, if it becomes clogged, opens an internal valve and dumps all of the accumulated crud into your engine. So you should replace the filter at every oil change just to be safe. And you should stay away from cheap full flow filters that come with leaky valves so they aren't really filtering anyway.

[Plymouthy Adams]

IF one was inclined not to do a complete oil and filter change, I would recommmend the change of the filter and cleaning of the filter housing, then top off the oil and at a minimum use a good additive like Rislone to the oil to boost its detergents..if the engine is just now getting switched to a detergent oil..the filter needs be changed lot more often as the detergents are slowly but surely cleaning the inside of the engine from the previous years of build up left behind by non detergents oils....just don't do what I saw being done to a top line BMW while on a trip to the mideast..remove the filter...rinse in gasoline and re-install..could not believe what I was seeing..