What should I use for oil in 40 Ford flathead?

[dp1743]

I'm new to this forum, so, please bear with me if I happen to step out of protocol.

I recently purchased a 1940 Ford Standard wih an 85 HP flathead eight. The engine has less than 1000 miles since it was professionally rebuilt and blueprinted. The oil is very clean, and, I'm not running a filter so I plan on changing it regularly.

My head is spinning with all the opinions out there, so I'm looking for help. I think I've got it narrowed down to either: Rotella T Triple Protection 15W40, or, Bulldog EO-O Premium Plus (for Mack Trucks) 15W-40. The problem is in decyphering the oil company's codes.
Rotella states it meets API Service CJ-4/SM (whatever that means), and, Bulldog states it exceeds API Service Category CJ-4. Both oils are designed for diesel engines. (The Mack oil I used in my F350 Powerstroke and it worked very well.

Do these oils have the Zinc in them that I've heard I should be using? If not, should I be using them in my flathead? I'd like to hear your thoughts on this.

[Ronnie]

10 30 any thing will do you well.

Quaker state pennzoil valvoline they are all good for todays rebuilds.

R

[Ol' Ron]

Ronnie has it right.

[Mart]

Don't overthink it. Just put in a good quality oil and change it regularly. You don't have a filter so you're not going to try and get 100,000 miles out of it before an oil change. Personally I use a 20w50 or 15W40 but whatever you use you will be changing it soon so don't worry.

[dp1743]

Thanks for that advice. Now... Should it be detergent or no? And, what about the zinc?

[Mike in AZ]

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welcome to the 'Barn....got pics of your '40??....you can do a search of the posts to see what has been posted before....don't know about the Bulldog oil, but the Rotella has been mentioned as a good oil to use....i think most of the oils mentioned have enuf zinc to work for the flatheads....lots better oils than were available in the days the cars were new....have fun....Mike

[41ford1]

In a fresh engine run detergent. Any of todays oils will be fine. In both of mine I add one blue bottle of STP at each oil change. Each of my two heaps gets an oil change every 1000 to 2000 miles or once a year which ever comes first.

[flatjack9]

Absolutely use a detergent oil.

[Bassman/NZ]

If your engine is stock, you do NOT need a zinc additive. Remember, when our flatheads were new there was no zinc in oil. However, if you are running an aftermarket camshaft and heavy duty valve springs you will need it.
Opinions are divided on diesel oil, some swear by it, some dont. Personally I think it has no place in a gas engine because the additives serve different purposes. Use a detergent oil, and as others have said, use whatever, it's all good.

[Jay in Mass]

Originally Posted by dp1743

I'm new to this forum, so, please bear with me if I happen to step out of protocol. Rotella states it meets API Service CJ-4/SM (whatever that means),

Welcome to the Barn. Whatever the question is, there are thousands of Flathead persons here who have "been there and done that". So don't be afraid to "ask", and enjoy the forum.

I happen to be using the Rotella in my Flatheads also. Would someone please us what CJ-4/SM means?

Would that be the zinc designation?
Thaks Jay in Mass

[Bluebell]

I wonder about this question as well. I read that the Flattie should run a mono grade oil because it works better with heat transfer in these hot (exhaust through the block) engines. This may be old news and modern oils may have left this behind. Any understandable comments from the oil gurus?

[Walt Dupont--Me.]

I use 15-40 Rotella I don't know what all those no. means on the container but you will find one of the no. it's usually the 2nd no. ( Cl-4) that stands for zinc. Walt

[Reds34]

The "C" in CJ-4 means compression (as in diesel), while the "S" in SJ means spark (as in gas). I read this from an oil post a little while ago.

Red

[mike42]

Valvoline racing oil 20w50 in my '40 Sedan 85hp. I change faithfully at 1500 miles. It has zinc in it. Sems to perform well.

Mike

[Henry Hopper]

http://www.classicmotor.co.uk/oil.htm

I just read through this article about oil for classic motors.In the past I have used Millers oil for Classic/ Vintage engines from the local motor factors.I need to contact the previous owner of my coupe to see what oil he has been using, as putting oil with detergent in into and engine that has been running on non detergent oil can cause blockage problems unless the engine is stripped and cleaned out first,, due to the new oil shifting all the crud that has built up over the years.

[GOW]

I had a old farmer tell me " dip ur finger and thumb in what you want to use for oil,then rub ur finger and thumb togeather,if they slip and slide use it if they stick don't use it" I use 20-50 castrol

[Graeme / New Zealand]

20/50 Castrol also.

GB

[Old Henry]

Changing your oil that frequently you might as well use the cheapest you can find. I use NAPA's straight S.A.E. 40 in the summer and 10W-30 in the winter.

[Ol' Ron]

What some people don't consider is the fact that the engineers that design these things have a better idea of what viscosity oil to use. The Flathead was designed to run 10 in the winter and 30 in the summer. Bearings need lubrication, But they also need cooling. The thinner oil removes the heat in the bearing. Heaver oil jut lubricates the pressure relief valve creating more heat. Modern engines use oils as low as 0/10. Using a hi viscosity oil just to see the gauge show 50lbs just means the relief valve is working overtime and the bearings are getting hotter.
IMHO

[GOW]

actually never thought of that....ol ron ur probably correct

[keith oh]

The greatest amount of wear is in the first few seconds after start up. The faster oil gets to the moving parts of an engine the less wear. One reason Diesel engines last longer is because thier fuel is Oil and therefor are lubricated from startup. So it stands to reason thiner viscosity oil is desirable. If an engine has not been run for a while (a day or more) then leave the ignition off and turn it over for 10 or 15 seconds. Then after 20 or 30 seconds, to let the starter cool, start it. That is why I think installing a stand by Electric fuel pump, just to prime the engine for a quick start after setting for a while, is actually harmful.

[VeryTangled]

Welcome to the Forums DP1743.

Those numbers are from the American Petroleum Institute's 'Service Classification' rating system. For starters, ratings beginning with C are for 'compression' engines, and S are for 'spark' engines, current production cars and trucks should take CH-4, CI-4 or CJ-4, or SJ, SL, SM, or SN. More in this .PDF: (don't recognize the .ashx extension, but it opens with Adobe Reader okay), http://api.org/oil-and-natural-gas-o...10_120210.ashx EDIT WRONG INFO: S=Service, C=Commercial as per the "Motor Oil Guide 2010."

It's a good question whether modern oil formulated for high compression, fuel injected, 200k mile engines, would be suitable for engines that originally used single grades not above SAE30 viscosity. As you can tell, there are quite a few perspectives.

-VT/Jeff

[dp1743]

Hi Mike. Yup... I'll be posting some pics in the near future. Thanks for your advice. Dick

[dp1743]

Thanks to everyone for their advice and for making me feel welcome. When it comes to oil we all know it's the "life blood" of the car. Makes me wonder though, when I was young I used to put used oil in my 56 Chevy 6 cyl. It came in glass bottles with long metal necks and a lot of old service stations would sell it cheap. I would stop to fill up on oil and check the gas. That car last another couple of years before it gave out. - Dick

[woodypecker]

SJ and CI have the most zinc but you can not find them anymore.

[lenmissy]

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I use no. 40 oil.

[tiger.1000]

In my Model B I use low detergent, SAE 30 but it ain't so hot in the UK

[Merc Cruzer]

20/50 Castrol and a bottle of ZZDPlus