Gas question, 1970 LS-5
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Safety Car
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From: Euless Texas
Gas question, 1970 LS-5
Is it ok to run a stock LS-5 on unleaded w/ no additives? Last time I had a car that it mattered was in the late 80's, and had a 390 Galaxie, and back then everyone thought you needed to add lead. I did a bit of research and it seems that the consensus now is that if the car isn't driven hard, that unleaded would be fine in an LS-5. Fact or fiction?
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St. Jude Donor '09
I think it has something to do with the valve seals. If you've got the original valve seals you need to add lead.....but don't quote me on that.
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From: Hohenems
Is it ok to run a stock LS-5 on unleaded w/ no additives? Last time I had a car that it mattered was in the late 80's, and had a 390 Galaxie, and back then everyone thought you needed to add lead. I did a bit of research and it seems that the consensus now is that if the car isn't driven hard, that unleaded would be fine in an LS-5. Fact or fiction?
Peter
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St. Jude Donor '13-'15, '17 thru '22
And which oil should I use?
If you do a search on this, you will find this one has been beaten to death dozens of times. Adding lead won't hurt your car, but it will hurt your wallet and our environment, but it's your car, so do what you want. I have been screwing around with cars from the late 60s and early 70s for 30+ years now, and have never had a problem running unleaded gas in engines of that era. When unleaded gas first came out in the '70s, the "common wisdom" was that without the lead as lubricant, the valve seats would wear prematurely. However, in about 1986 or so, leaded gas became unavailable, and we didn't see a rash of worn out heads shortly thereafter, so I think the concern was overstated to say the least. Some engines in extreme use, did and do have problems with the new fuels, but generally street engines have no issue with unleaded fuel.
I own a 1970 LS-5. I don't use any fuel additives. So far, I haven't had any problems with fuel. Be careful of snake oil salesmen.
If you do a search on this, you will find this one has been beaten to death dozens of times. Adding lead won't hurt your car, but it will hurt your wallet and our environment, but it's your car, so do what you want. I have been screwing around with cars from the late 60s and early 70s for 30+ years now, and have never had a problem running unleaded gas in engines of that era. When unleaded gas first came out in the '70s, the "common wisdom" was that without the lead as lubricant, the valve seats would wear prematurely. However, in about 1986 or so, leaded gas became unavailable, and we didn't see a rash of worn out heads shortly thereafter, so I think the concern was overstated to say the least. Some engines in extreme use, did and do have problems with the new fuels, but generally street engines have no issue with unleaded fuel.
I own a 1970 LS-5. I don't use any fuel additives. So far, I haven't had any problems with fuel. Be careful of snake oil salesmen.
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Is it ok to run a stock LS-5 on unleaded w/ no additives? Last time I had a car that it mattered was in the late 80's, and had a 390 Galaxie, and back then everyone thought you needed to add lead. I did a bit of research and it seems that the consensus now is that if the car isn't driven hard, that unleaded would be fine in an LS-5. Fact or fiction?
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Not only do you not need it, your spark plugs will last alot longer without the lead. Many of us have been driving our old Corvettes for MANY years with unleaded fuel with no problems. Just run the 93 octane and you will be fine. As Mike said, these myths die hard 
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Safety Car
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From: Euless Texas
The last time I dealt w/ this was in the late 80's when I was a teenager, and the consensus then was that you always had to add lead. I see now that is not the case, which is good! A buddy just picked one up, and we were curious, as neither of us have any real experience w/ pre-emissions/high compression engines.
Thanks all
Last edited by Vettin08; Apr 5, 2010 at 01:47 PM.
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From: Crossville TN
Use any good-quality oil of the viscosity level required by your location and driving conditions. Change it at regular intervals and your engine will appreciate it. If you have a super-high-performance engine, use oil and additives that are appropriate for your engine's needs.
I have a SB base engine that is usually pampered and not abused. I use Mobil 1 full-synthetic 10W30 oil which I change once a year [or so]; but I change the filter every 2000-2500 miles.
I have a SB base engine that is usually pampered and not abused. I use Mobil 1 full-synthetic 10W30 oil which I change once a year [or so]; but I change the filter every 2000-2500 miles.
Drifting
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From: Fl
Use the 15w-40 HD deisel oil.
It contains zinc, which is not added to any of the modern oils. On older flat tappet engines it is needed to aid in lubrication between the cam lobe and lifter.
Do a google seach on inc and engine oil - there are some very informative articals out there.
As for lead - add it if it makes you happy, but for normal driving you will not have isues with valve seat recession.
I have added TEL to fuel and on my car, the engine will idle smoother and I swear it runs a bit cooler.
Drawback - it fowls the plug out in 3-5K miles. Changing them plugs on an LS5 is a bitch if it has AC. The unleaded fuel will give you 4-5 times the plug life..
my 2 cents..
It contains zinc, which is not added to any of the modern oils. On older flat tappet engines it is needed to aid in lubrication between the cam lobe and lifter.
Do a google seach on inc and engine oil - there are some very informative articals out there.
As for lead - add it if it makes you happy, but for normal driving you will not have isues with valve seat recession.
I have added TEL to fuel and on my car, the engine will idle smoother and I swear it runs a bit cooler.
Drawback - it fowls the plug out in 3-5K miles. Changing them plugs on an LS5 is a bitch if it has AC. The unleaded fuel will give you 4-5 times the plug life..
my 2 cents..
