oil
 

Is 5 w 30 to thin for a 36 flathead?

Re: oil
 

Lots of different opinions on oil. What to stay away from is oil marked "For gasoline engines only" as this is oil for the modern roller engines. Personally, I wouldn't use anything lighter than a 10-40.

Re: oil
 

In my opinion, the answer is 'Yes' - I think even a straight 30W would be better than a 5W. BUT - I have not attempted to try it, so this is just a gut feel.

Re: oil
 

I like lighter oils, but I think 5w 30 is too thin myself, I would want something heaver weight. Same as Bored&Stroked nothing to back that up.

Re: oil
 

Ol' Ron will check in. I THINK I remember him saying that he liked 5w-30. Of course, he's in Vermont.

Re: oil
 

>>>Is 5 w 30 to thin for a 36 flathead?>>>

I've only used Motorcraft 5w-20 synblend since rebuilding my 21-studder 6 years ago. So 5-30 might be a bit too thick when it's hot. 8^)

Jack E/NJ

Re: oil
 

I think these oils are designed more for the roller lifters/followers and the heavier oils for a flat tappet cam. But Jack says it works for him, so I guess only time would tell if there is a ware difference. It may have more to do with the additives than the weights, I'm certainly no oil expert!

Re: oil
 

I use straight 30 wt. for the limited season we have.

Re: oil
 

My 1980's snow-blower manual says 5w-30 below 32 degrees. But since we're not driving snow-blowers on highways and interstates, and that I live only a two-hour drive south of Canada, I choose to use 10w-30 in my 59AB that has 35,000 on its rebuild. Gauge reads 70 lbs cold and 15-20 lbs hot. I currently have no filter on it, change the oil every 1000 miles, drive it at least an hour each run, and don't need to add oil between changes. So I'm good for now.

Re: oil
 

I use straight 30 weight down here in the sunny, but cold at the present time, South.
Does me proud.

Re: oil
 

If your flathead has not been rebuilt, chances are it's an original engine or was rebuilt some time ago. That would mean using a straight weight non-detergent oil ad Henry did. If the engine is older running a detergent oil could cause you some problems. Others hopefully will chime in here on this subject as well ....
If it is rebuilt I would use 20w-50 as I have in all of my rebuilt engines with a bit of zddp added and I run no filter but change my oil frequently ....

Re: oil
 

I use either Chevron Delo 400 or Shell rottella 15-40. been using it for 15 years in my stock 8cm '51 Merc.

Re: oil
 

"Is 5 w 30 to thin for a 36 flathead?"

No, it's not too thin. Why would you think it's thin?

Oh ... the 5W.

After all that's been written about oil, it is amazing how few understand the numbers.

First the "30". That is a viscosity GRADE, not a weight. So 5W30 has a grade of ... 30. So-called "straight weight" 30 also has a grade of ... 30 ... and is labeled SAE30. Both have a viscosity flow approximately the same at OPERATING temperature.

0W30, 5W30, 10W30 and 20W30 all have a viscosity grade of 30 at operating temperature.

What's 5W? The W means WINTER. It does not mean "thin". It does mean that when it's cold, your oil will not flow like molasses but will try to flow closer to 30 grade, bur not thinner. It's not going to be some weak, watery stuff.

At cold (cool) start up, even in the South, SAE 30 ("straight weight") is thicker than it is at operating temperature. Most wear occurs at start up ... why would you use that crap when a multi-grade oil (note it's not called "multi-weight") will lubricate your engine better?

5W, 10W, etc. all indicate the oil's ability to flow closer to the viscosity grade when the temperature is below operating level.

If you want a 30 grade oil, pick the Winter rating you want. Keep in mind that the stuff they put into the oil to do this viscosity magic can break down with extended or extreme use like racing ... but for our engines, old or new, multi-grade is the only wise thing to use.

Note:

"In my opinion, the answer is 'Yes' - I think even a straight 30W would be better than a 5W. BUT - I have not attempted to try it, so this is just a gut feel."

(Same thing happens to me. Stay away from broccoli.;))



.

Re: oil
 

Have you looked in the owners instruction book---it depends on the temperature

I only have a 1937 listing--
above 90 degrees--- 50wt
100-30 degrees --- 40wt
65--20 degrees--- 30wt
50--0 degrees--- 20 or 20W
30-- minus 15---- 10 or 10W
-10 or lower --- 10wt + 10% kerosene


From this listing it would appear that 5W 30 would be good from 65 degrees down to well below freezing

Re: oil
 

Thanks Hoop, very informative! I looked up the temperatures used to establish the ratings, that is interesting as well (at least to me). The straight SAE viscosity is measured at 100 deg C (212 deg F). The W SAE viscosity is at various low temperatures. It would be interesting to see a viscosity curve between the low and high test points to see what the viscosities are at the temperature ranges that a flathead runs at.

Re: oil
 

In my humble opinion, your advice is the best thus far.
These old flat head engines do not have the tight tolerances of today's engines and as such require thicker weight oil for proper lubrication effect.
Thinner weight oil is utilized primarily in tighter tolerance engines.
Anything less than straight 30w on a used flat head is too light in my opinion. On a rebuilt, most likely to tighter tolerance than Ford produced, yeah, a high quality 20w/50 is to me, perfect.
Our new Mercedes requires 0w/50. yep, you read that correctly - ZERO w/ 50. I can only imagine the tight tolerance built in this engine. And hey, I was a tool maker... I know tight tolerances!

Re: oil
 

Straight 30 in winter months?

Re: oil
 

I agree with TomT and Kube. I have had 2 flat heads rebuilt by a professional re builder. He recommended 20-50 as well as ZDDP. I live in Ohio and basically only drive in summer.

Re: oil
 

'That would mean using a straight weight non-detergent oil ad Henry did. If the engine is older running a detergent oil could cause you some problems."

Kube, you think that's the best advice? So-called "straight weight" is killing your engine on cold starts.

I explained that "weight" is an incorrect term ... it's GRADE when you are talking about viscosity. Oil is not labeled by "weight."

Not sure what your point is on the 0W50, but if you are saying that the "ZERO" means it is a really thin oil, you need to reread my earlier post. What Mercedes is saying is that it requires 50 Grade oil at operating temperature ... and wants to prevent that 50 GRADE from getting any THICKER when the engine is started cold with cold oil.

No matter what one's opinion is, using the correct terms and understanding what multi-grade oil really is helps the discussion.

Many folks completely misunderstand multi-grade oil. If an engine runs best on a certain GRADE oil at operating temps, then it will run best cold on the same GRADE. The problem that oil companies have solved is that straight GRADE oils are thicker when cold and the GRADE changes. Modern oils attempt to maintain the same viscosity through a temperature range from cold starts to operating temps.


.

Re: oil
 

Here is my response. Fresh major rebuild of a 226 G 6 cylinder flattie, less than 10 hours. running 10w30, sitting idling in my drive while I wash the car. At some point I get in to move it and see NO oil pressure. I have no idea how long it ran that way. Motor now has just a slight rattle it didn't have before. Changed oil and went to 20w50 just to see if that would help as I was told 10w40 was too thin for the type oil pump I had. Nothing helped. I finally took the engine back apart, had the oil pump machined to get the clearances tighter and now run straight 30w. NO problems since. was it the oil pump or the oil I do not know. I was told by a guy that knows that style oil pump NEVER run less than 30w in the G series 6 cylinder because of that style oil pump. I was told by the same guy that once the film in the pump disappeared because of thin oil it would not pick up oil again until I primed the pump, because it hangs above the oil not submerged in it.

Re: oil
 

Hoop,
I've read your bit a couple o times now, what's not clear from your posts is the difference between the 0w 5w 10w and so on. To be clearer here. It wants say 50 "grade" when hot it still wants the same "grade" when cold. So why is there different W grades for 50 grade oil? If 0w is the 50 when cold in a 0W50 oil, then what is 5w with 50 grade? And 10W and 15W and so on, they can't all be the cold grade of 50 can they? One of them is right all the others can't be? Can they?
In the charts posted above the grades are clearly marked viscosity. So thin to thick?
I'm no oil expert, but it does definitely say viscosity!
Please enlighten me, I like learning stuff, but I question a lot. Thats how I learn.
Martin.

Re: oil
 

Engine Oil Viscosity Chart
Numbers indicating what viscosities are like in the winter at the north pole.
0 gasoline
5 kerosene
10 diesel fuel
20 sewing machine oil
30 maple syrup
40 cornhead grease
50 crankcase sludge


Jack E/NJ

Re: oil
 

Scooder, 0w, 5w, etc. refer how cold the oil can get and still maintain the desired viscosity. Simply, 0w can stand more cold than 5w.

For other stuff, if folks are interested, go on-line and start reading. No use in my trying to rewrite what is already there. Try to think logically about what the oil companies and auto makers want to do with oil. Some of the things guys post do not make sense.

Re: oil
 

With this logic in mind - 10-30 in winter and straight 30 or 20-40 in summer is ideal. I think:)

Re: oil
 

This is an informative discussion. I was told about 25 years ago, before synthetic oils were popular, that the ingredient that the oil companies put in oil to make it multi-grade displaced lubricants. The greater spread between the "W" number and the highest number, the less lubrication in the oil. e.g. 10W-30 has more lubrication than 10W-40, etc. Maybe things have changed since then, but I try to use the highest "W" number for my climate and maintain the grade oil recommended by the manufacturer. For what other reason would there be so many "W" ratings? Why not make all multigrade with a 0 "W" rating?

Re: oil
 

Ok, from my recent reading! The w number ends up being the weight/grade of the oil, the addvatives allow it to perform as the higher number. Over time the oil can degrade toward the w weight/grade. This is mainly do to factors that are not encountered with a flathead (such as extremely high temperatures).

Re: oil
 

As usual, contentious comments are all over the place and that is normal. These engines actually have fairly close tolerances when they are in properly overhauled condition. They are a carbureted engine so the oil gets more contaminants than our modern computer controlled cars. This only means that they have to have short schedule oil changes like every 2,000 to 3,000 miles or so due to more impurities and bypass type filtering if there is any filter at all (like the older engines). As to SAE viscosity ratings, they were designed for SAE 20 to 30 ratings for average cold to normal conditions. The only reasoning for higher viscosity would be as a fix for worn bearings with low oil pressure readings or looser tolerances for more power output.

The same things hold true for the modern multi-viscosity oils. The W is for winter operation or cold weather. An SAE 10W/30 rating is now the all year average oil by the OEM specs. Warmer weather can use 10W/40 or even 20W/50 but I would only use the 20W/50 if I had higher piston clearances for forged pistons or an extremely worn engine. The polymer plastic stuff that they put in the oil to give the higher viscosity breaks down faster on engines with carburetors so it still has to be on a tight schedule for oil changes, maybe even tighter than the straight grade viscosities.

Most of the 5W/?? or 0W/?? oils are so the modern cars will get all the advantages (crank windage) for mileage that the governments set forward. Same with skinny tires mounted on newer vehicles. They do every trick in the book to make them pass the standards. I would only use these oils in modern fuel injected engines. I still use SAE 10W/30 in all my modern 4-wheeled vehicles and 10W/40 in really hot weather.

Any oil is better than none but some are definitely more appropriate than others depending on ambient temperatures, area conditions, and how the engine is being operated.

Re: oil
 

It states in the owner's manual that you should use SAE 40 between the temperatures of 100 degrees and 30 degrees. I live in Massachusetts and the temps in the summer are no higher then the mid nineties and the spring and fall are in the 40's and 50's. those three seasons will be my driving time. So I suppose I should use the recommended oil. I'm thinking that today's oil is probably better, though, because the technology for refining it is better and we have had 80 years to experiment and learn.

Re: oil
 

Just listen to Hoop. That being said, here is what I use to judge if an oil is the right thickness. After the engine is warm, I see oil pressure at idle and at 3000 rpm. At idle, if it's at least 6 psi for ~600 rpm, it's good. If it's at least 30 psi at 3000 rpm, it's good. If it's pegged when HOT at either point, it's too thick or something is wrong. If it's not at least these numbers, go to a heavier grade until you get at least 10 psi/1000 rpm.

Got this from bobistheoilguy and that's how I do it for everything now.

Re: oil
 

Here is the info

Re: oil
 

And then on the flip side of the coin, In the commercial world I use rotella 15-40
in a 1950 F6 V8 salt sander. It may run 24hrs straight, and then it may idle for
5 or so hours "we never shut trucks off in storms" oil gauge needle runs little past
the center all day & night and idling. My 65 yr question on these 48-52 oil gauges
how come being a 80lb gauge and (30lb) is in the middle? don't cha think it should
be 40lbs???? but a test mechanical gauge reads 45lbs so why the 30??????

Re: oil
 

Being a few years old and bimetal based that aint to bad...and you can calibrate them.
There are 2 settings of a KS meter to adjust it.

Re: oil
 

Just one little problem with the oil of today...its not designed to be superior to the engine only...its designed to be enviromental safe...not clogg up catalytic converters...give you a magic mileage...and other non engineering political BS.
And some of the oilwells had very low sulphur contents giving a clean oil to start with...not sure if any company today own the entire process of their oil.
I use a 15/40 from a farmsupply company here has the highest zddp i found in a non special oil today.

Re: oil
 

flatheadmurre brought up an important point - the ZDDP content for our flat tappet cams. Almost ALL of the modern oils we see are for late model engines, with catalytic converters and roller cams. The friction reducing compounds have been stripped out of them.

So, regardless of the oil viscosity you run (and brand), make sure you have high enough ZDDP compounds for flat tappets (1200 or so) - or put in an additive in (especially during initial fire and break in).

I use Brad Penn - Penn Grade 1 break-in oil (30w) and their multi-viscosity Penn Grade 1 afterwards. They have the right levels of ZDDP and other additives for high-performance flat tappet cams.

Re: oil
 

A lot of people have stated the "magic " number of 1200 for flat tappet cams. Look at the oil in the 80's - 600ppm of ZDDP (Pennzoil 10-40). Assume earlier years had a lot less. Where does this magic figure come from?

Re: oil
 

Everyone is still thinking overhead valve. When the flathead was introduced, they never heard of ZDDP.

Re: oil
 

ZDDP is related to high valve spring pressure on flat tappet cams in OHV engines, not much of a concern in a flathead.

Re: oil
 

So why wouldnt we take advantage of a product that gives us a longer life of the cam and tappets ?

To avoid metal scuffing we have a few different aproches.

1. get an oilfilm in between...thats fine with a bearing that can contain the pressurised oil...not as easy with a tappet first slammed into the lifter and then dragged sideways...it can sure use a bit of help here.

2. we start adding somthing else the metal can slide on without scuffing beside the oil....all kinds of fancy metals has been tried here, This is the aproach ZDDP is taking.

3. Chemical additives affecting the metal.
Ok we dont want scuffing...what can we do to avoid it besides keeping metals from hitting each other ?
If we add something that lets the metal transform instead...its not magic...if we have some chemicals bond to the metal letting the high spots hitting each other fold over and become a smoother and harder surface instead of wearing off.
This is the aproach of an additive like X1r.

So will the engine run on a non dergent singlegrade oil with a minimum of additives ?
Sure it will !
Its a wonderfully forgiving engine.
The additives of your choice is to get an extended lifespan and less maintenance...

Re: oil
 

Most modern oils contain ZDDP. Additional ZDDP should not need to be added above what is already in the oil for a flathead (if you select an oil with it in the first place}. But some additonal additive is most likely not going to hurt unless you over do it. If the ZDDP level is to high it can become harmful.

Re: oil
 

When Do I Need ZDDP the Most: The time when I'm most concerned about the levels of it in my oil is during the initial break-in of a new engine, with a new flat tappet cam and lifters. The first 15 - 30 minutes of run-time have a whole lot to do with overall camshaft/lifter life.

Having a good break-in oil with high levels of ZDDP and other additives is a very smart thing to do. I use the Penn Grade 1 30W break-in oil. After that, I'll still run a oil with higher levels of ZDDP - as it surely won't clog your catalytic converter that you don't have on your flathead - so why not use it!