Diesel Oil or No

[RLJ]

A lot off the early L series heads had brass or bronze seats and they sunk with leaded gas!

I don’t think the oil made any difference with those brass seats sinking. 

[Crashtd420]

Did little looking to see what an acceptable oil would be, i found some conventional oil specifically for the flat tappet cams and has more zinc and stuff than regular oil.....

Of course the rotella is on this list of high zinc oils... 

Rotella was the Cheapest... about $20

The valvoline and Lucas around $35

And the synthetics around $50 or so ...

 

 

Valve line vr1, and the Lucas  have a 10w30 non synthetic oil... 

 

 

 

 

Edited April 15 by Crashtd420

[datzenmike]

23 hours ago, iceman510 said:

Similar to concerns about valve recession when lead was removed.  It was concern for older cast iron heads that did not have valve seat inserts.  Datsuns has hardened inserts in the aluminum heads, so no worries. 

 

Disclaimer:  This applies at least to the Datsuns I have owned (mainly L and Z series).  I don't know for certain if vehicles like a 320, Roadster or J-engine cars have separate valve seats, so don't jump on me with exceptions.  😁

 

Can't imaging older cast iron heads not having seat inserts. How would you rebuild the heads if not removable? Everything was rebuildable back in the day.

[datzenmike]

1 hour ago, Crashtd420 said:

Did little looking to see what an acceptable oil would be, i found some conventional oil specifically for the flat tappet cams and has more zinc and stuff than regular oil.....

Of course the rotella is on this list of high zinc oils... 

Rotella was the Cheapest... about $20

The valvoline and Lucas around $35

And the synthetics around $50 or so ...

 

I thought someone on here said that the cost of synthetics was close to that of conventional oils?????? I haven't looked lately but it used to be extreme.

 

T4 is $40 for 5 L and T6 is $60 locally and that's 50% more.

[iceman510]

7 hours ago, datzenmike said:

Can't imaging older cast iron heads not having seat inserts. How would you rebuild the heads if not removable? Everything was rebuildable back in the day.

 

Imagine all you want, because after all you do believe you know everything.

 

https://www.enginebuildermag.com/2025/01/valve-seat-materials-and-machining/#:~:text=There are two types of,iron%2C that's what they were.

 

[datzenmike]

Now you're just being a dick. I didn't say that all heads had inserts or that I knew that they did. Imagining and knowing are two different things.

[ggzilla]

Datsun started using stellite valve seats in 1970 i believe, that were rated for the upcoming unleaded gasoline. Stellite was nothing new, but it was expensive. Cost of the hardened seats, extra machining costs, extra assembly costs

 

Cast iron heads, at least all the ones I worked on, had no seat inserts -- they just machined the seat right into the cast iron. They were still rebuildable, you used a valve grinding machine to re-cut the seat. I had a Souix machine to do it. I only worked on 1950s-1970s heads but if they were cast iron, they had no removable seats. Many american V8s didn't even have the 3-angle valve job that Datsuns left the factory with

 

But this has nothing to do with the oil. It was the lead in the gasoline that let the old valve seats survive. The solution to valve seat wear was the old one: use hardened seats

[datzenmike]

Wouldn't machining sink the valves? Or could you cut the heads and install seats?

 

Was Phosphor Bronze used on the intakes? This is a U67 head so '75-'77 only and you can see the yellowish insert.

 

 

[ggzilla]

re-cutting the seats does not sink the valves, at least not past spec. The FSM has details. The valve guides are some kind of bronze alloy, but the seats are not on 1970s Datsuns

[datzenmike]

Can you find out more about the intake seats I have? They don't run anywhere near as hot as the exhaust so a different alloy. I heard phosphor bronze for it's hardness. Don't know but they are definitely yellow in color.

[iceman510]

4 hours ago, ggzilla said:

But this has nothing to do with the oil. It was the lead in the gasoline that let the old valve seats survive. The solution to valve seat wear was the old one: use hardened seats

That article also mentioned that some cast iron heads may have had induction hardening of the area of the seat.   It also discusses the lubricating effects.

[iceman510]

4 hours ago, datzenmike said:

Now you're just being a dick. I didn't say that all heads had inserts or that I knew that they did. Imagining and knowing are two different things.

Sorry to the OP.

 

I'm not the one being a dick.  I made a true statement, and you as you often do, felt the need to refute or question it, despite the fact that you clearly had no idea.  Your weak defense of your statement above "I didn't say..." is just typical.  Clearly your initial response was intended to say I was wrong.  

 

Please don't waste any more time on your defense, as I won't respond.

[ggzilla]

1 hour ago, datzenmike said:

Can you find out more about the intake seats I have? They don't run anywhere near as hot as the exhaust so a different alloy. I heard phosphor bronze for it's hardness. Don't know but they are definitely yellow in color.

That's a good point. The exhaust valves would need a better seat, so maybe when Datsun said "hardened valve seats" it only applied to the exhaust. The salesman books (introduction service bulletins) full of random details like that

 

Copper alloys have been used for a long time for valve seats but I thought phosphor bronze wasn't very special, and copper-berillium is what they used on race cars. So likely there are various type copper alloy valve seats. I haven't seen any Datsun or Nissan docs that talk about it. Stellite nickel alloy was a go-to in the 60s and 70s, I have no idea what today's mass market engines use, probably something cheaper than nickel-alloy I would imagine

[datzenmike]

2 hours ago, iceman510 said:

Sorry to the OP.

 

I'm not the one being a dick.  I made a true statement, and you as you often do, felt the need to refute or question it, despite the fact that you clearly had no idea.  Your weak defense of your statement above "I didn't say..." is just typical.  Clearly your initial response was intended to say I was wrong.  

 

Please don't waste any more time on your defense, as I won't respond.

 

Only you could take offence. If I thought you wrong I would damn well say so. I can only talk to my experience and that is, heads with removable seats. Then don't respond and I have the last word. You're a dick, for being a dick.

[Ooph!]

I spoke with my friends at the machine shop, I work on my own stuff there but I only dabble.

 Datsun aluminum heads did come with inserts but they weren't sure of exactly what metal, they thought beryllium for the exhaust and the intake was a softer metal.

From memory unleaded was supposed to be an issue for older engines and that was why leaded continued to be sold in California until 1992 IIRC.

 Some cast iron head valve seats were cut into the casting I've seen them, was told they were induction hardened.

[john510]

Mobil 1 has a high zinc oil specifically for older engines. I saw the ad in Hagerty Classic magazine. Why are all of these oils 10w-30 ? I guess for V-8's ? 

[ggzilla]

They are 10W-30 because that's what older engines used, including all Datsuns and 1980s Nissans

24 minutes ago, john510 said:

Why are all of these oils 10w-30 ?

[john510]

28 minutes ago, ggzilla said:

They are 10W-30 because that's what older engines used, including all Datsuns and 1980s Nissans

I always thought our Datsun's were 10-40 or 20-50 in warmer climates ? No ? 

[Ooph!]

This is from the 74 620 FSM

I also remember there was some resistance to multi weight oils kind of like Synthetic oils now

 

 

 

As I was looking at the page this just appeared lol

 

 

 

Edited April 18 by Ooph!

[ggzilla]

It's also in the glovebox owner's manual. 10W-30 was the most common oil for like 40 years. 10W-40 can run up to 230 degrees IIRC. But our Datsuns run around 180-200 degrees and the oil inside the engine is about 10 degrees hotter than the coolant temperature

 

And yes, Nissan recommended unleaded fuel in their 1970s models as your photo shows

[ggzilla]

I was thinking about this. At the time the 1974s came out, there were no cars that required no-lead gasoline. Yet Datsun was ready, their cylinder heads were designed to run on unleaded. The first "cats" came in late 1974 that's what required unleaded fuel

 

Contrary to the hundred of web pages that say catalytic converters were mandatory for 1975, it just aint true. But GM wanted you to think that. What was mandatory was a drastic lowering of smog-inducing NOx, and the only way to meet that was with cats ... or with advanced Japanese technology. Meet e.g. Honda's CVCC and Datsun's B210 engine technology, which had no cat in 1975. Datsun added it for 1976, but after that was able meet emissions limits without a cat on some models. Nissan was working on the same idea as Honda (Nissan NVCC) but in the end didn't need it

5 hours ago, Ooph! said:

This is from the 74 620 FSM...

 

RECOMMENDED FUEL

Use a no-lead or low-lead gasoline

[datzenmike]

On 4/18/2025 at 12:32 PM, john510 said:

I always thought our Datsun's were 10-40 or 20-50 in warmer climates ? No ? 

 

The w is a rating of how well it flows when cold. Lower numbers mean easier starts and better faster lubrication which is what you want at 10 below. Otherwise all oils are about the same viscosity when at warmed up engine temperatures. Thicker oils in the winter are not a good idea.