Oil Change Interval on a 41 Flat6 ?

[GTfastbacker]

Hey,

 

since my 41 runs like a champ the odometer accumulate miles by miles.

I am now at rough 3.000 mls since I got it.

 

I did an oil change as I got it, incl. filter. I had to add only 1.5 quart while these travels. Oil pressure is still at 25 - 60 PSI. (idle/ driving)

 

Now I am wondering what will be a good interval to change oil with our modern oil and these vintage bypass oil filter ???

 

Thank you

Joe

 

[Sam Buchanan]

Joe, I don't know the "best" interval to use but I can tell you what I do. I usually change oil in the '48 P15 yearly (or when I get in the mood to do it) which is less than 2000 miles. The spin-on bypass filter gets changed every other oil change. I use a 10W30 oil. You will get a lot of opinions on your question, probably not much consensus. 

 

But considering the low quality of oil in use when these engines were daily drivers back in the day, and for which these engines were designed, we probably change oil much more frequently than is actually needed.

Edited September 23 by Sam Buchanan

[plymouthcranbrook]

Since for various reasons I never seem to accumulate many miles on my 52 Plymouth I tend to do changes every two to three year regardless of milage.

[Los_Control]

Yeah nobody will agree .... My daily drivers I change the oil every 6 months, fall and spring. I drive less then 6K miles a year with 2 vehicles so they get changed with less then 3K miles on them.

 

I think my habit was born from the past years and lesser quality of oils .... the belief was that after 6 months use the oil will start to deteriorate in performance.

This may not be true with modern oils.

 

Then I use a cheap super tech brand of oil from walmart that claims it is good for 5K .... It just does not cost that much $$ to change the oil and keep it fresh.

I think the oil change procedure is part of a ritual to check the car over and get it ready for summer or for winter. Check the tires, belts, grease any areas that need it or address any issues that need it. .... changing the oil is just a pre-determined date for me to give the car maintenance.

 

[Tom Skinner]

GTFastbacker,

I agree with Los Control above, the habit of doing spring/Winter settings at the carb and choke coincide with my oil changes etc., etc., 

Tom

[JBNeal]

additional information - service station oil change interval

[Young Ed]

I personally wouldn't go in over 2k with a flathead but it also depends on the driving. Are you doing lots of 5mile trips or lots of interstate drives?

[GTfastbacker]

4 hours ago, Young Ed said:

I personally wouldn't go in over 2k with a flathead but it also depends on the driving. Are you doing lots of 5mile trips or lots of interstate drives?

 

I go mostly longer trips with 50 to 150 mls each. No short trips.

[Sniper]

I would not take any modern-day oil recommendations for oil change intervals on our cars. Those recommendations assume you have a quality full flow oil filter something most of us do not have.

[Eneto-55]

Consider some general conditions:

All paved roads or lots of dirt roads (The latter was pretty much assumed during that era, for sure where I came from, rural Oklahoma. It is also the case here in Holmes County Ohio, especially due to the type of places I go in my work - mostly gravel or dirt-gravel back roads, with some chip & seal, very little actual paved road ways)

Time intervals (as others have already mentioned)

 

I look at the oil, and evaluate the viscosity of the oil.  When it starts to get really black, I change it. Or if it doesn't hold a sort of web between my fingers. (But our current family car takes 0 - 20 weight oil, and it feels almost as thin as ATF.) Of course I also track the mileage, and consider the time span since the last change.

 

(Just my thoughts - no warranty involved.  )

[desoto1939]

I basically change my oil and filter ever two years. Also I base this on the amt of driving that I have done. I have a 1939 Desoto that also has the bypass filter. The older oil can style stated that you could go 8k on an oil filter because it was a bypass filter and not a full flow filter like we have in our modern cars.

 

I also replace my oil bath filter element with a NAPA paper element that fits perfectly in my air cleaner housing.  I feel that since inmy area we do not have dirt roads and the old tar/chip roads the amt of dust and other air quality junk has lessened so I change the filter when it needs to be done and also blow out the filter every year.

 

I also use the new Castrol GTX Classic that has a very high amt of ZDDP and it is a W20/50.  This oil can NOT be used in a modern car becasue the modern cars have catalytic converters and this oil will destroy the converter.

I know a couple of posters on the forum do not like the Castrol oil products but the oils of today even the Walmart brand is totally better than what was being used back in the 30-50's.

 

I think the biggest issue is that you check the oil and the mileage and then make your our personal decision when to change oil and filter. I feel that both should be done together.

 

The real big culprit if only starting your engine and not letting it get upto full operating temp and then radiator temp thermostat is not fully open the you get water and other acids building up in the oil pan which is not good for the car.  So in the winter time if you start you are in your garage let the car fully warm up and get the temp to be above where the thermostat opens.

 

At lot of people change the oil before putting the cars away for winter storage becasue the water and acid issues. some prefer to start the year with fresh oil every year, again a personal choice.

 

Also at the end of the year is the perfect time to check all the fluid levels and to test the antifreeze quaity.  In out older cars you should be usin ghte OLD GREEN AF that is labeled as INT inorganic and not the modern AF like the extended fomulas.

You will have to look for the old green AF but the auto stores still carry this product.  

If you AF is still good and not showing any signs of turning brown and is still green I also dump in a bottle of Water Pump Lubricant and Anti-rusting agents.

AF breaks down as it gets older and you start to loose the antirusting agents so that is why it turns brown.  The protection of frezzing is still there but th einternal rusting chemicals have been depleated.

Also make sure that you also have the correct style radiator cap. Some of the early cars used a non-pressure cap and then they started to go to pressure caps.

If you over fill the radiator some of the systems will purge the extra fluid in the radiator. In my 39 Desoto which is non-pressure system the water level is approx 1 inch down from the top of the tank.  Let you car determine what is best for your cooling system.

 

Also time to check the battery fluid level and also take a reading of the electrolites in each cell. Most caps can still be removed, but do not overfill ech cell. The original rubber bulb filler has a small hole approx 1/4 inch above the end of the filler tube.  This was there so that when tested the fluid it would suck out the extra fluid if it was overfilled.  The new bulb do not have this over fill hole.

 

I have a older document on batteries that describes this information.

refer to the attachment. This info was taken from my Autolite Battery Manual

Rich Hartung  Desoto1939@aol.com

 

 

[greg g]

I am going on 5k since last change. Tractor Supply 15w 40 all fleet oil. Car will be going for annual state inspection  some time in Oct.  Will get oil and filter changed while its there.  Going on 55k since rebuild and install. Use Napa 1080g element. Operates at 42 to 45 psi on the gauge.

Just had it in for our P15 Picnic pre-tour check. Checked hoses, belt, fluids.  Added a smidge of differential lube, pinion seal is dripping a bit.  Added 1 pint of engine oil prior to 550 mile jaunt. Still above add line

[Plymouthy Adams]

Do what makes you happy, do what you know is right..!!!

 

 

[kencombs]

To bad we don't have a computerized 'duty cycle' counter on the dash.   I'd really like to tabulate number of starts, % of run time at normal operating temp, average trip length, oil temp, and a host of other things to decide when to change. 

  Maybe just 'cycles' which is used in a lot of aircraft maintenance plans.  

A cycle, is a takeoff and landing.   max power, less power, cruise power, landing stress etc all play into the plan.

  Way to complicated for cars I think so I just go by gut feel,  If the oil doesn't get hot enough to remove the moisture regularly, but does get used often, every six months change 'seems' OK.   More miles, less short trips, yearly or 2000 miles 'seems' right. 

 

When I get my rebuilt (really a high class overhaul), pickup engine together it will have a full flow system, and maybe the bypass too, and the highest temp thermostat I can find and I'll go to a 3000 mile interval, 5000 if using synthetic and driving every day.

[Tom Skinner]

Joe,

I wish we all could agree, but it is your call, your car, change the oil when you see fit.

I have owned 1948 Chryslers for over 50 years, they like their oil changed every 1,000 - 2,000 miles.

Why I don't know, they just turn it black and useless every 1 -2 K Miles. 

Maybe its because the Engine Block is Cast Iron or Whatever.

I'm sure the environmental wonders will disagree, But with 50 Years experience I don't care what anyone has to say about it.

Choose your system.

Tom

[Plymouthy Adams]

they turn their oil black early as they are an inefficient engine.....now that is not to say they are not reliable and rugged and will live a long life and serve you well, just don't expect it not to pollute.  Get them late in life without a tear down in their history, even with the better maintenance schedule, you will be years cleaning that engine with normal oil changes given that you are also continue to add to the inefficiency.   

[GTfastbacker]

Thank you gentleman,

 

i will follow your advice and change before winter storage and then latest after 2,5K mls

 

Joe

[1949plymouthdeluxe]

I used to work on a lot of tractors, lawn mowers and whatnot. I also own a 1996 Tacoma 4 banger I bought new. I've never thought much about oil. I usually get whatever is on sale. 15W-40 for diesel engines is usually the cheapest. Never had a problem. The tacoma now has over 300,000 miles. 

 I too was curious about how dirt the oil gets in these. When I got the car I changed the oil when I first got it, changed it again a few weeks later just because. The new oil looked like it had been in there for 10,000 miles. Pretty much black.

[greg g]

I worked with a guy who had a Tacoma.  He was talking about taking his drained oil to the local Napa to turn it in.  He had acouple of plastic dairy cartons with oil in gallon milk  jugs in his bed.  Thestuff looked brand new.  I asked him how often he changed it.  He said 1500 miles. His commute was 60 miles per day, he used the truck for towing lawn mowers and stuff for his week end side jobs.  At the time I had a S 10 with 150k on it that was a beater with a heater, and tow vehicle for my Ice Racing car.  Both these vehicles liked oil.  So I told him I would take his used stuff.  Except for oil changes of my wife's car, I didn't buy any oil for four or 5 years. It was a sad day when he retired.  As for oil turning black, that's the detergent working, breaking down carbon, encapsulating the partials to keep them in suspension and delivered to the filter.  It's the breakdown of additives, and degradation of lubricity that determines oil life, not just because it's black.  IMHO.  in 60 years of driving 40 plus vehicles, i have suffered 0 oil related engine failures.

[Los_Control]

I have to admit, engine failure I have had was not because of poor oil quality ..... any type of oil would keep them running.

 

How well you maintain the engine is the key.

 

Same with body, suspension, brakes, tires, moving parts  ..... this applies to my daily drivers as well .... A 1993 Dodge Caravan that would drive anywhere

Because it has been taken care of ...... same deal with my 1991 chebby truck.

[1949plymouthdeluxe]

 The engine in these reminds me a lot of the tractors and other agrarian type equipment we had when I was younger. And I remember all we ever did was just buy whatever oil happened to be on sale. Didn't matter if it was walmart, some weird no-name oil from the dollar store, or 15W40 for diesel engines. Most important thing that mattered to us was to frequency of the oil changes. And we were pretty fastidious  about that so we really never had a problem.

 For a while I did small engine repair on the side. And I would get people's push mowers in that it probably literally never had the oil changed. And what came out was some sort of primordial ooze and I thought to myself how in the hell did that thing run!?

Edited October 1 by 1949plymouthdeluxe