I’ve been adding lead substitute to the gas tank of my "68 Buick Riviera, but I wonder whether this is really necesary. Any thoughts on the subject (hopefully from people with more car knowledge than I have) would be welcome.
IMHO lead sub is not necessary in cars made after the early '60s.
Amoco offered a lead free gas since the late 1920s.
Save your money…Your valves will be fine…
When leaded gas began to disappear years ago, some of the cars built before 1975 suffered valve damage. Lead, being a soft metal, was needed for the “unhardened” valves to cushion the impact on closure.
Having said that, it appears some cars were sensitive to it, while many others were not. I never understood why. Perhaps some were using hardened valves all along.
Miller oils description is just a tout sheet for a useless product that they make…
My vote is for your Riviera being just fine without any additions.
It’s also my understanding that some GM cars of this era used cast iron with a higher proportion of nickel in it and that aids the valve seats.
Back in 1990 I bought a 70 Cadillac. I used lead additive for a couple of years until I ran out and just never bothered to buy more. I drove the car about 5000 miles a year, including 3 trips to Vegas from Seattle. In 1999 I sold the car to a friend who used it as a daily driver for 5 or 6 more years, including towing a u-haul from Washington to Texas. It finally developed a misfire from low compression. But at that point it had 240,000 miles on an original engine. I doubt lead additive would have made any difference.
@ok4450, off-topic, but it is my understanding that Oldsmobile engines are the ones with higher nickel content, and that also it helps prevent corrosion when used in a boat. I always wondered why I saw Olds engines in boats.
My father and I never used lead substitute in my father’s 1969 Dodge Dart, and that thing seemed to run forever.
I am not going against any ones comments here as it depends on the engine…This pic was taken from a 64 Thunderbird 390 V-8 4BBL after it was ran with unleaded gas for 20 years after the lead was removed.
This is the exhaust valve that has eaten into its valve seat using unleaded gas…Now I ran my 68 Ford Pick-up ( work truck ) for many years using unleaded with no problems 302 V-8 … I guess it depends on the engine…I remember my dad saying that Amoco used to call it " white gas " This pic was taken by me when we tore down the engine for a re-build on my buddies 64 T-Bird…
I worried about my '57 Chevy when unleaded gas first came out. I never used a lead additive and the engine ran just fine with no damage. I think the general consensus of people in the maintenance arena is that lead was never needed in the first place.
In these older cars, 1960 and older, a “Valve Job” was considered standard maintenance at around 70K miles. Few of these old cars made it to 100K miles without a valve job. And they all were fed leaded fuel…Better materials, design and technology led to the much longer engine life we enjoy today…
@missileman: “I think the general consensus of people in the maintenace arena is that lead was never needed in the first place.”
…and I think those who had valve problems always attributed the problems to unleaded gas, even when there might have been other causes.
I thought lead was a cheap way to boost octane
“I think the general consensus of people in the maintenace arena is that lead was never needed in the first place.”
I would not call it a general consensus. Lead definitely had a secondary effect of cushioning the impact of the valve on the seat. When examining valves that were burned out, it was easy to see those with severe valve seat recession.
As noted though, not all engines seemed prone to it.
Vehicle manufacturers started installing hardened valve seats in their engine in the mid-late 60’s. This was done because they knew that the EPA was going to phase out leaded gas in the 70’s. Mostly because the EPA required that most vehicles sold in the U.S.be equipped with catalytic converters.
So it depends what year the vehicle was manufactured if there would be a problem with the valves without leaded gas.
I used Amoco unleaded 102 octane in my 56 DeSoto back in the day with no ill effects, in fact it stopped my plugs from lead fouling.
My early 70’s Ford truck 302 V8 has been run on unleaded for 200K miles w/no problem that I can discern. A prior poster (Howie) said the same about his Ford 302 V8. Compression, engine performance all fine for me. I must admit, I don’t drive the truck much these days, and I haven’t removed the head and looked at the exhaust valves. There could be a problem lurking. But with a 40 year old truck, I expect that anyway. (Just recently, I had to super-glue the tube that runs from the exhaust manifold (the heat pipe that heat’s the carb’s choke) as it rusted loose. There’s a kit that’s supposed to be used to fix this problem, but my auto parts store doesn’t have it. I just looked at the repair yesterday and it is still holding. That’s life w/a 40 year old truck.)