The Stovebolt Site Forums The Shop Area General Truck Talk Lead Substitute?

I learned to drive in an old '74 IH Scout that took leaded gas. When I was part-way through high school (late 80s) - leaded gas was discontinued. We switched to unleaded, but for a few months, we used lead-substitute. As I recall (and I might be full of it), the lead was supposed to improve engine life.

(Here's my question)
So, in an old engine (40 - 50+ years), does anybody here use lead substitute in the tank? I still see it on the shelves at the auto parts store. Have you made engine modifications to run unleaded, or, have you just switched to unleaded without experiencing problems?

First off practically everything built from 71 up was built for unleaded gas even though leaded was still available. It seems like the older engines don,t give any problem if not driven hard. I ,ve had a bunch of them & never added anything & never had a problem. A fleet of trucks I used to work on switched to propane, in spite of my advice not too. The Fords wallerd out valve seats in a few miles but the chevy,s seemed to do OK.

I used the lead substitute for a few years but can't really vouch for whether it is worthwhile or not. As part of the latest rebuild I had the machine shop install the hardened valve seats which is supposed to be what is necessay for burning of unleaded. Folks more knowledgeable than I are sure to chime in with their experience on this one.

When I was 15 I lied about my age and got a job at a gas station working 3rd shift.

That summer, the only time I ever saw anyone buy or use lead additive was one really old dude who put a can in with every fill up.. his car was some mid 70's sedan, that probably didnt need the leaded gas anyway.

I'd like to know how an engine designed to run with leaded is different from an engine designed to run unleaded.. it would also be cool to know what the average octane rating was for gas back in '46 thru '50

We use it in some of the old farm equipment that still works hard for a living, mostly old tractors and the like,
Scott

The 235 that I rebuilt for my 52 did not have the hardened exhaust valve seats installed. Two of the exhaust valves were burnt in less than 10,000 miles. The previous owner did not run lead substitute.

Add about 4 to 6 ozs. Marvel Mystery oil to a tank of gas will do as much good as the lead substitute

It seems that the old inline sixes are OK using unleaded as long as they are not driven sustained high speeds.

However, the older high compression V-8's probably should use an upper cylinder lubricant like Marvel Mystery Oil. As V6 jimmy says, it works just as well, and it is more economical to use than the other products.

Not necessary.
I do throw a little marvel mystery oil in my Malibu every fill up for no particular reason.

Got hopped up 1959 and 1955 235s. Unleaded is all what we get here in Germany.

Both are driven on German Autobahn with permanent 70 and more mph over long distances. Even to Italy over the Alps and steep mountain passes. One is also abused in quater mile races, no problem ever.
Non of my hot rod friends and the stovebold enthusiasts over here use any additive. Tough the Ford guys have to use some if they race, not for cruising... for some reason I don`t understand :confused: .

Here in Germany lead in gas was invited in 1955
so all the pre war and early post war engines can handle unleaded. Not sure if it was the same in the US.

many greetings from sunny southern Germany, Frank

A book I read on auto restoration said that an engine that ran leaded long enough had enough lead embedded in the valve seats to protect them. Newer head rebuilds should have hardened seats as a matter of course. Shouldn't need lead substitue unless you install an NOS head without changing the seats.

we blend our racecar gas(ms98l contains tetraethl lead from vp racing fuel) 50/50 with pump for our stovebolts and restored tractors but they have very limited miles one tank a year if it was higher consumption it would get spendy

rh

Lead was originally added to gasoline back in the 1920s to reduce knocking - it is a cheap way to incease the octance of gasoline. I remember back in the 60s that octance ratings of 100 were common, at least when you bought premium gas (it was commonly called "ethyl" back then".

Been driving my 235 on unleaded gas for 15 years. If I ever rebuild the head I might go to hardened seats but maybe not. An old timer was told me to add one cup of Auto Trans Fluid (ATF) to every tank of gas. Being naive I thought if one cup would work, a whole quart would work better! Not true! It hissed and popped and smoked until the gas tank was empty! Never tried it since.

My father in law swears by putting some Marvel Mystery Oil in old engines at fillup.. it must be working, because both his super M's purr like a kitten.. and they're OLD OLD OLD tractors.

Besides raising the octane of gas,tetraethyl lead was found to improve the heat transfer from the exhaust valve to the head.Exhaust valves can run red hot,when they do,micro welding can occur each time the valve is on the seat for that very brief time.After a time,the micro welding errodes away the valve seat and or valve.Lead,or valve seats made of errosion resistent materials lessen this.
On many old engines the carburation is on the rich side which keeps the valve cooler with less micro welding.52 PU suggested loosing the valve clearances a bit so the valve stays on the seat longer,tranferring more heat to the head and guide.
Mystery oils added to the engine oil won't do a thing for valve seats.Most farm gas tractor engines had valve seat inserts or induction hardened seats as does many heavy duty engines designed for continious full throttle service.