Leaded Gas???

[pidge]

Hey guys, I got asked twice now by different people who just got talking to and they both had asked me if I have to run leaded gas. I said I don’t know, I’ve never even gave it a thought. My question, do you guys and gals run an additive in your fuel tank to make the gas leaded? Benefits if there are any?? I hope to god I haven’t ruined something by not adding it. All I e done is fill her up with 93 octane that has no ethanol from Shell. Thoughts from anyone with more insight into this. It’s my 69’ 521 with the big 1300 I’m referring about. Thanks. 
-Pidge

[datzenmike]

Leaded gas was an octane booster that is now replaced by up to 10% ethanol. Older engines also benefited from it's lubricating properties on the intake valve seats. Older engines used a bronze valve seat that is 'soft' and without lead it will wear faster and the valve will 'sink' up into the seat. It doesn't happen overnight so don't worry. If and when you rebuild they probably will, but specify newer hardened seats like all makers switched to back in the '70s.

 

ZDDP

I would recommend that you use an engine oil that has the same ZDDP, a zinc anti scuff additive, as when your engine was new. Cars today don't use cam on lifters or cam on rockers and don't require as much. In addition it's not good for today's newer catalytic converters, so yearly the amount of ZDDP has been reduced by at least half by oil makers from what it used to be. Oil makers say that the newer formulations are reverse compatible with older engines and that the older levels were too high to begin with. I'm not buying this. (this is just my opinion) My Datsun valve train to too valuable to replace from using a sub standard oil. I suggest you look up the ZDDP controversy and decide for yourself. You can buy extra additive or specify a 'racing' oil or simply use an oil with the same high levels like I do. Diesel oils still use cam on lifter and their oils are still high and exempt from lower levels. The easiest thing is to just reach for a different oil when you change it. I use Shell Rotella T4 15w40 but have just switched to 10w30 having learned the lower viscosity is available too. Chevron Delo 400 is also good. Esso also makes a diesel oil. Note that I only drive in the summer and 15w40 would be way to thick for Ontario winters. (I'm sure you won't be driving your L521 in the cold)

[DanielC]

I just looked through a manual for a  PL-521, no mention of the octane rating of the fuel.   I have mostly ran regular E-10 in my 521 trucks, however I did experiment with running higher octane, with slightly advanced ignition timing.

You can adjust the ignition timing more advanced with higher octane fuel.   This will give you slightly more power, and slightly better fuel economy.   You should also get a gallons per mile increase, running non ethanol, simply because gasoline has a higher energy content than ethanol.  

 

You might get a performance increase by advancing your ignition timing.   But do not advance it so far you get spark knock, or detonation.  Advanced that far you lose power, and hurt engines.

 

I use Valvoline VR-1 racing oil in my Datsuns, it does have the high ZDDP content.   I believe all the cylinder heads I have have either been rebuilt with hard intake valve seats, or are modern enought to have them.

 

 

Your trucks actually looks pretty good under the hood.

Edited June 20, 2020 by DanielC

[datzenmike]

My '76 710 L20B recommends unleaded gas with an AKI (anti knock index) of 87 and a RON Research Octane Number of 91. Thw '73 and '78 620 service manuals say the same. I just run 'regular', there's nothing lower than 87 I believe. I've traveled in the US and notice no difference in running.

[Dguy210]

54 minutes ago, datzenmike said:

My '76 710 L20B recommends unleaded gas with an AKI (anti knock index) of 87 and a RON Research Octane Number of 91. Thw '73 and '78 620 service manuals say the same. I just run 'regular', there's nothing lower than 87 I believe. I've traveled in the US and notice no difference in running.

 

I've noticed a significant difference in power between the 87 regular and 92/93 ethanol free, with an A14 and Hitachi carb it was literally the difference by a gear going up a hill. Not as big a difference with the weber but still observable. But there is also a small gas station in the wide spot in the road near where I live that sells it for all the small engines so I use that exclusively. Not a big fan of the downside of ethanol based fuels. 

[datzenmike]

I've heard of these downsides but never seen them. All our gas is up to 10% ethanol. My car sits all winter in the rain and starts and runs fine every spring. My gas trimmer goes years on a gallon of mix. Both sit out doors under cover and 4 or 5 pulls it fires up and away I go. For the first time in the 7 or 8 years I've had it I pulled the spark plug. Clean as a whistle light tan/cream, I put it back.

[pidge]

On 6/20/2020 at 10:26 AM, datzenmike said:

Leaded gas was an octane booster that is now replaced by up to 10% ethanol. Older engines also benefited from it's lubricating properties on the intake valve seats. Older engines used a bronze valve seat that is 'soft' and without lead it will wear faster and the valve will 'sink' up into the seat. It doesn't happen overnight so don't worry. If and when you rebuild they probably will, but specify newer hardened seats like all makers switched to back in the '70s.

 

ZDDP

I would recommend that you use an engine oil that has the same ZDDP, a zinc anti scuff additive, as when your engine was new. Cars today don't use cam on lifters or cam on rockers and don't require as much. In addition it's not good for today's newer catalytic converters, so yearly the amount of ZDDP has been reduced by at least half by oil makers from what it used to be. Oil makers say that the newer formulations are reverse compatible with older engines and that the older levels were too high to begin with. I'm not buying this. (this is just my opinion) My Datsun valve train to too valuable to replace from using a sub standard oil. I suggest you look up the ZDDP controversy and decide for yourself. You can buy extra additive or specify a 'racing' oil or simply use an oil with the same high levels like I do. Diesel oils still use cam on lifter and their oils are still high and exempt from lower levels. The easiest thing is to just reach for a different oil when you change it. I use Shell Rotella T4 15w40 but have just switched to 10w30 having learned the lower viscosity is available too. Chevron Delo 400 is also good. Esso also makes a diesel oil. Note that I only drive in the summer and 15w40 would be way to thick for Ontario winters. (I'm sure you won't be driving your L521 in the cold)

Thanks Mike, that’s some good info. I’ve read elsewhere they had lead in gas to help prevent some sorts micro welds from happing on the valve seats and the valve seating surface....I got to do a few more little items that have crept up lately on the 521, but when I do I’ll have a look for the Shell Rotella 10w-30. And your right to assume I don’t plan on driving that truck during the winters here. Thanks man agin for the lesson. 
-Pidge