Do flatmotors need zinc additives?

[37FordPickupTucson]

I have been told that zinc additives were not in the motor oil when my '37 85 HP V8 was built and to not worry about it. Is that true? I have Chevron Delo 400 in it. That worked fine in my PowerStrokes, is it OK for my flatmotor?

[delco1946]

I believe that is true, but..... the gas also had lead. The research I’ve done suggests that since gas has no longer has lead that a bit of zinc in the oil is helpful for the seals. Some people think it’s helpful and other don’t think it makes a difference. I don’t know anyone who says it’s bad so worst case senario I feel like I’m just wasting my money, best case I’m helping my engine.

[JSeery]

The "Zinc" helps with flat tappet lifters with high valve spring pressure. Most flatheads run low valve spring pressure. You can read endless discussions on the topic in past threads.

[philipswanson]

Don't need zinc but you shouldn't be running diesel oil. Too much detergent. If it's a clean motor, run high viscosity synthetics.

[Tinker]

Isn't that the idea behind harden valve seats? Most run MMO also for the upper engine lubrication. Just run some decent 10-40w and a shot of MMO.

Just for fun... what was the "octane" rating in the 30s-40s-50s.

I know if I get my hit/miss hot enough I can run just about anything in it, just as contaminated and dirty gas as I can give it. But octane was around 40 then.

[flatjack9]

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Zinc has not been totally eliminated from today's oils, just reduced. Still plenty for our flatheads and yes it was not in oils when your engine was built.

[Drbrown]

Whether its a flat-tappet/mushroom stem valve flattie, or an overhead valve Cadillac V8 known for soft cam lobes, there seems to be a consensus to add some zinc, especially during an engine break-in period, and since the government has had the amount of zinc in lubricating oil significantly reduced.

For my '47 Ford and '84 Caddy I add Rislone zinc and phosphate mix in varying amounts based on their prescribed schedule.

Any discussion of gasoline octane ratings needs to be related to an engine's compression ratio.

[Tinker]

Originally Posted by Drbrown

Whether its a flat-tappet/mushroom stem valve flattie, or an overhead valve Cadillac V8 known for soft cam lobes, there seems to be a consensus to add some zinc, especially during an engine break-in period, and since the government has had the amount of zinc in lubricating oil significantly reduced.

For my '47 Ford and '84 Caddy I add Rislone zinc and phosphate mix in varying amounts based on their prescribed schedule.

Any discussion of gasoline octane ratings needs to be related to an engine's compression ratio.

Octane was just a side note, this question has been discussed many times before. But fuel certainly has an effect on the upper end of a motor was well. Zinc or lead... Do you add lead additive to your fuel also?

[40 Deluxe]

The correct answer is "NO"!

[flatheadmurre]

You can run just about anything and it´s better then the oil back then...just think about the short maintenance intervals back then...
I said it before Zinc and phosphor is the best oil additive invented and only reason it´s taken away(it´s not completeley but reduced) is that it hurts catalytic converters.
You don´t need a crazy amount of zinc but it´s not going to do anything but protect you engine...so why not have it ??
That diesel oil should have much more detergent then modern "car" oil is starting to become false, the egr system and other emission control systems has forced car oil to contain a lot of detergent additives today.
My thinking is that a flathead which is a "dirty" motor compared to a modern one does quite well with a 15/40 diesel oil.
And with the low mileage and pampering we do to our cars all this is probably overthinking the issue

[4t8v8]

Been running Mobile Delvac 15W/40 Diesel oil in both of mine for years with excellent results. Add a little MMO once in a while. I also use PCV and my engines stay very clean.

[flatjack9]

I have never added any zinc additive to any of the engines I build or drive and have never had one problem.

[flatheadmurre]

Originally Posted by flatjack9

I have never added any zinc additive to any of the engines I build or drive and have never had one problem.

Additives is never a good solution...a well enginered oil contains what is needed and is tested to work by the manufacturer.
Even adding a break-in additive is a gamble compared to a ready enginered break-in oil.
Most oils still have zddp and phosphor as additives it´s just that the emission control issues and lifespan of catalytic converters demand them to be lower then what a pure performance engineering point of view would like.
Other additives are available but so far nothing with as good performance for the same low cost.
And with risk of sounding like a broken record...you don´t need a crazy amount of zinc...absolutely no need to ad something like a break-in additive.
But zddp is still the best oil additive invented imho...nothing is more bang for the buck in preventing metal to metal galling.

[jrvariel48]

Besides the debate that it may or may not be needed, will it hurt anything to put in an additive like Rislone?

[JSeery]

Yes, too much additive can be damaging. There is really no need to mess with this stuff, but if you must, do it in moderation!

[flatjack9]

The oil companies spend millions of dollars to perfect their oils and then people think they can improve on them with a bottle of who knows what. I don't get it.

[mike42]

I have to chuckle every time this topic comes up. When I was a kid driving a '50 Ford flathead I ran the hell out of that car and put in whatever oil was available. Never had a engine knock or problem. What killed that motor was a cracked engine block in a very cold Michigan Winter as I didn't pay attention to anti-freeze at the time !!! NOW....I pamper the hell out of my '40 like it was a new born baby ! How things have changed. I run Valvoline Z-1 with Zinc with a new filter every year.

Without causing another long thread on this matter....has synthetic oils been successful in flatheads ?

Thx....Mike

[flatheadmurre]

Just stay away from synthetic oil during break-in...otherwise it´s like icecream we all like different flavours !

[mike42]

Lol

[G.M.]

Originally Posted by 37FordPickupTucson

I have been told that zinc additives were not in the motor oil when my '37 85 HP V8 was built and to not worry about it. Is that true? I have Chevron Delo 400 in it. That worked fine in my PowerStrokes, is it OK for my flatmotor?

Why not use a better oil, who knows but it may extend the engine life
a few years?? The oil with the best additives for your diesel is Cummings
Blue made by Valvoline. Read the attached oil tests and how good oil
is made. I use this in my diesels and a few of my old Fords. G.M.