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Old 02-20-2018, 04:39 PM   #1
oldforder
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Default Oil viscosity (weight) for model A

So from reading old posts I gather that people use most everything from 10w30 to 20w50, and everything in-between, with some even opting to use non detergent. I personally believe that non detergent is not for internal combustion engines but I am not here to argue that point. My concern is the viscosity of the oil. My engine will never be started in temperatures below 60f. If it is, I will first use the oil pan heater, which raises the oil temp quite rapidly. My concern is the type of oiling system used for the main bearings in these engines. The Idea of a high viscosity oil having to flow through what I consider a quite small passage to lube a large bearing. It seems like one would want a quite thin oil, at least when cold. So, would a 0w40 oil be superior to a 20w50??? ALSO, it sits quite a while, like a couple weeks at a time in the summer between uses, and 5 or 6 months over the winter, and I want something that will leave a film on the bearings till oil gets to them when starting. I will put only probably 1 or 2 hundred miles a season on it, and will change the oil every fall like I do my other classics.
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Old 02-20-2018, 04:54 PM   #2
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Default Re: Oil viscosity (weight) for model A

This will help you a lot. Its only a few pages long and will give you great insight.

http://rmaford.org/wp-content/blogs....C_Mar_2012.pdf
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Old 02-20-2018, 05:01 PM   #3
J Franklin
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Default Re: Oil viscosity (weight) for model A

Clearances in your antique car are much larger than your modern rig. 10-30 or 10-40 are the only choices you need to make.
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Old 02-20-2018, 05:20 PM   #4
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Default Re: Oil viscosity (weight) for model A

We have owned our 1929 Sport Coupe for 40 years. Drive it about 200 miles per year and change oil ever spring.

We use 20-50 Walmart oil (four quarts) along with one 16 oz blue bottle of STP. Marvel Mystery Oil in gas.

Oil pressure in summer after car has been driven 20 or so miles 3 to 4 lbs.

Good compression (all mid 60’s), no valve noise, never over heats.

Everyone has their view, but this has worked for us. Enjoy.
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Old 02-20-2018, 06:35 PM   #5
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Default Re: Oil viscosity (weight) for model A

1930-Pickup, thanks for posting an informative link.


Not much doubt that a 'modern' multi-weight oil is the best but no one provides at what engine temperature does this magic transformation take place. I suspect to get the full advantage of a multi-weight oil it is necessary to also use a modern thermostat in your Model A.


For your consideration, 20 years ago I called the Pennzoil consumer hot line and asked for their suggestion. " With the clearances in an engine that old" they suggested a straight 30w.
Since then I've tried all the combinations.


My '28 does not have a thermostat and since the thrill of driving in sub-freezing weather no longer excites me, I've returned to Pennzoil's suggestion.


'Your mileage may differ.......'
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Old 02-20-2018, 06:53 PM   #6
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Default Re: Oil viscosity (weight) for model A

Right now I have 15w 40 oil plus a bottle of STP. I think this should give me good residual lubrication for start up, and be good for hot weather , but I guess my main concern is if it is to thick to run down the passages to oil the mains. If you are running 20w50 plus the STP, I guess Mine should be ok though. At least if I am not starting it in very cold weather, which I won't at least not with out warming up the oil as I said.
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Old 02-20-2018, 07:03 PM   #7
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Default Re: Oil viscosity (weight) for model A

20-50 oil is good for 15f to 110f. 20w at 15f, 50 at 110f.

Our Model A without a thermostat runs around 165 degrees in summer after good drive. Water only with rust inhibitor.

A well maintained Model A engine, driven only in summer, I do not believe needs a thermostat. 90 years, what has changed?
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Old 02-20-2018, 07:51 PM   #8
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Default Re: Oil viscosity (weight) for model A

There is no end to the question of oil...............
Here is another choice that is high (2000 ppm) in zinc.
SCG has 20% sales often and have had a 30% off that I took advantage of.

https://surfcitygarage.com/oil-acces...motor-oil.html
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Old 02-20-2018, 08:17 PM   #9
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Default Re: Oil viscosity (weight) for model A

I use 20-50 or 10-40 synthetic in all my model As.
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Old 02-20-2018, 08:24 PM   #10
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Default Re: Oil viscosity (weight) for model A

I have also seen some run oil formulated for diesel engines. What is the benefit over "regular" oils?
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Old 02-20-2018, 08:59 PM   #11
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Default Re: Oil viscosity (weight) for model A

Quote:
Originally Posted by 1930-Pickup View Post
This will help you a lot. Its only a few pages long and will give you great insight.

http://rmaford.org/wp-content/blogs....C_Mar_2012.pdf
This is an interesting paper to read. Mostly accurate, although there are some fairly serious typos in there that give incorrect guidance to the reader. Do not follow it blindly. And it's 6 years old, so might be a bit out of date.

For example, do not use 40 weight oil in winter and 20 weight in summer, even though that's what it says on page 11. That was a brain fart (easy to do on a long paper that you have been staring at for weeks while you write and edit it).

Most guys over think and over worry about oil. The most important things are to make sure you have ENOUGH of it in the engine (but don't overfill) and change it OFTEN. If you do that, your engine will outlive you. And don't over advance the spark or lug the engine; that's really rough on the bearings and NO oil out there will save them.

Besides the typos, there is also a lot of often repeated misinformation in this paper about zinc and ZDDP. Caveat emptor.

Contact the oil manufacturers and get the zinc facts from them, not from an anonymous author on the ahooga.com forum website (or this forum website, for that matter). It is easy to get the facts from the Tech Support hotlines at Shell, Chevron, Mobil, etc. Ask them for the zinc levels in their different oils. I have had spec sheets emailed to me. Very easy. You will discover that they vary by oil type and weight, and intended use. If you choose the right oil, you can get the wear resistance you think you need.

Here is one:
https://cglapps.chevron.com/msdspds/...&docFormat=PDF

Here's another...
https://mobiloil.com/~/media/amer/us...pecs-guide.pdf

Henry had no ZDDP in his Model A oil. Mustang engine owners claim to need high ZDDP, and they may be right, but I don't have a Mustang engine in my Model A, so how is that relevant...

As I said, most guys over think and over worry about oil. Go out and drive your car!
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Old 02-20-2018, 09:02 PM   #12
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Default Re: Oil viscosity (weight) for model A

Indeed, the use of a straight 30 weight oil recommended by many Model A forums may lead to a lack of lubrication quality. The use of an oil similar to "Henry’s Oil", especially if much care is not taken by the owner, will result in an engine needing rebuilding sooner than an owner using a modern oil. " END QUOTE "


This is an opinion of two Guys, B. S. too Boot.


You don't run thin oil in a splash oil system. What I refer to as thin oil is, among many, is say 10W.30. Dump it out of the bottle, and it looks like 30 Wt., then dump it out of a hot motor, and it looks like P!$$ Water.



Take some of that and rub between you thumb, and index finger, it doesn't slide very good.


Now do that with 30Wt. Detergent, you will find it to be one heck of a difference.


30Wt. Summer.


20Wt. winter.


We work with bearings every day, and have, 54 years.
A bearing that runs thin oil, runs with larger clearances. The reason being there is more friction on a thinner oil film, and way less cushion.


We have never recommended anything else.


Yes, just about all oil will work, but compared to what!


Herm.

Last edited by Kohnke Rebabbitting; 02-20-2018 at 11:03 PM.
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Old 02-20-2018, 10:05 PM   #13
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Default Re: Oil viscosity (weight) for model A

Our conclusion is that the use of the higher cost Synthetic Multi-Grade 10W-40 Motor Oil for newer Model A engines is justified since it has a benefit in terms of a higher temperature margin for preventing cylinder wall scoring. " END QUOTE "


Higher Tem. Margin, OK. But cylinder wall Scoring comes from pistons fit to tight. I have seen that hundreds of times. Never set clearance to what comes in your piston box!




The oiling of the cylinder walls is accomplished by scoops (dippers) on the connecting rods. These dippers pick up oil from the corrugated sheet metal pan and create a "fog" of oil that lubricates the pistons and cylinder walls. " END QUOTE "


Oiling of the cylinder walls, done by dippers, NEVER, the dippers are there only to oil the rod. What puts oil on the cylinder walls, is the crank, and the rod as a whole, kicking the oil out of the dipper tray.


I have heard many times that the two holes in the web, are there to oil the cylinder walls. NOT TRUE, they are to relieve air, and oil locks that would take place in the top of a dead end X groove.


Herm.











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Old 02-21-2018, 12:57 AM   #14
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Default Re: Oil viscosity (weight) for model A

Hi Al. Your car doesn’t need the zinc additive. It was more for cars in the 40’s and 50’s etc. with stiffer valve springs.
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Old 02-21-2018, 01:02 PM   #15
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Default Re: Oil viscosity (weight) for model A

1. All of the sludge filled engines I have disassembled used non-detergent single viscosity motor oil.
2. The higher the oil's viscosity, the more energy it takes to pump it, and it flows slower due to the effect of gravity. Oil to the crankshaft bearings and camshaft bearings flows via gravity through small holes.
3. Synthetic oils have a higher operating temperature and a higher squeeze-out resistance. Oil pressures in the main bearings is THOUSANDS of psi. Also valve lifter to camshaft faying surfaces benefits from higher squeeze-out.
4. The cost of synthetic oils have come down to be competitive with non-synthetic oils.
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Old 02-21-2018, 03:26 PM   #16
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Default Re: Oil viscosity (weight) for model A

A question(s) for Mr. Kohnke: Assuming a stock 'A' engine with Babbitt bearings, how long after a cold start can it safely run without oil reaching the mains (or refilling the dipper tray)?
Now, say your A has sat in an unheated garage for a month. You go to start it tomorrow morning when it's 14 above. How long before oil reaches the mains and dipper tray?

I'm going to say a cold engine will run a lot longer (without any damage) before oil gets to the bearings than the average person would think. Or else no Model A would have made it past it's first winter!
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Old 02-21-2018, 05:14 PM   #17
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Default Re: Oil viscosity (weight) for model A

Oil does not evaporate in a months time and surface tension should keep some of it in the bearings. Even if the oil did drain out of the valve chamber there should still be oil in the bearings and dipper trays. Guess you could do an experiment, take two pieces of plexiglass say about 2 by 3 inches, spread some oil on one and press together with .015 clearance between the two. In a months time look and see how much oil still remains between them.
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Old 02-21-2018, 06:49 PM   #18
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Default Re: Oil viscosity (weight) for model A

Quote:
Originally Posted by redmodelt View Post
Oil does not evaporate in a months time and surface tension should keep some of it in the bearings. Even if the oil did drain out of the valve chamber there should still be oil in the bearings and dipper trays. Guess you could do an experiment, take two pieces of plexiglass say about 2 by 3 inches, spread some oil on one and press together with .015 clearance between the two. In a months time look and see how much oil still remains between them.
Very true. I have taken apart engines that have sat for years and there was still oil in the bearings. But, my question was, How long can that engine run, without damage, on only the oil remaining in the bearings, before gravity supplies more?
I may get ambitious and rig up a tube and funnel, pour some oil in on a cold morning, and see how long it takes for various viscosity oils to flow through.
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Old 02-21-2018, 07:15 PM   #19
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Default Re: Oil viscosity (weight) for model A

When I was much younger and didn’t know any better. My first Model A lost oil pressure on the way home from the gas station I worked at after school. We had just put the oil pan back on after cleaning the sludge out.

I would say that car was driven about five miles with the oil pump not working.

Put car on lift, took oil pan off, reconnected oil pump correctly, refilled with the old oil. Than back on the road home. It ran fine until I graduated from high school. Enjoy.
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Old 02-21-2018, 09:47 PM   #20
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Default Re: Oil viscosity (weight) for model A

Quote:
Originally Posted by 40 Deluxe View Post
A question(s) for Mr. Kohnke: Assuming a stock 'A' engine with Babbitt bearings, how long after a cold start can it safely run without oil reaching the mains (or refilling the dipper tray)?
Now, say your A has sat in an unheated garage for a month. You go to start it tomorrow morning when it's 14 above. How long before oil reaches the mains and dipper tray?

I'm going to say a cold engine will run a lot longer (without any damage) before oil gets to the bearings than the average person would think. Or else no Model A would have made it past it's first winter!

The oil in the dipper tray is always full after the engine shuts off.


When it is 14 above, you should have had 20 wt. oil in it already but if it is still 30Wt., There wouldn't be but a few seconds difference, if any. Those Model A Oil Pumps really put out. I had a 31 Model a coupe with a box in the back that I drove in the winter hunting. the oil wasn't changed very often, and it had 30Wt. year around, never any problems with bearings, and it sat out all year, by the chicken house. pull up once, and it was running. In any case, the oil would be there, before the heat from the bearings would be.
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