fuel additives

[john henderson]

should I use a lead additive in my 65?

[Jon S]

Yes

[55 cadi]

Unless your engine was worked on for new unleaded gas.

My 66 mustang was changed over for the new gas so I didn't have to add lead additive.

Believe different rings and valves done for the new gas. Can't remember all that gets done.

[Bobby B]

My 66 mustang was changed over for the new gas so I didn't have to add lead additive.
Believe different rings and valves done for the new gas. Can't remember all that gets done.

Please inform me on what the "Changeover" was, because I would like to get in on it.    I have no idea what Type of rings would be used in a stock engine running Unleaded fuel vs. Leaded fuel. Most old school stock engines run some form of a cast ring when rebuilt with no problems whatsoever. Yes, hardened valve seats would be the proper thing to do if you had the heads off and were in need of a valve job, but to be honest with you, I've never witnessed any damage done to a stock motor in a classic car because of using Unleaded fuel. And if the seats took that much of a pounding, you must be driving that car an awful lot and at a constant high RPM. I personally, have only experienced a few  minor problems due to the ETHANOL in the Fuel, not the unleaded Fuel itself. Add a little MMO and call it a day, unless you're looking to rebuild your engine anyway. Just my 2 cents.......
                                                    Bobby

[35-709]

 "I've never witnessed any damage done to a stock motor in a classic car because of using Unleaded fuel."

Agreed.  Unless you are rebuilding, taking the heads off for hardened seats is unnecessary, and I never used any additive in my '60 Coupe, the 2 '66 Cadillacs I had, or any other car I have owned for that matter.

[jdemerson]

John,

   On my 1952 Cadillac I have been using Motor Medic lead substitute (made by Gunk) with each tank of 91 octane Ethanol-free  gasoline. For winter storage I add Stabil fuel preservative (Marine grade).  As far as I recall, this is consistent with what at least some others on this Forum have recommended in the past. Of course this is the kind of issue where opinions are sure to vary.

John Emerson

[Jay Friedman]

I wasn't aware that unleaded fuel could harm piston rings.

20 years ago or so, I had a valve job done on my '49's cylinder heads and had hardened exhaust valve seats installed to deal with unleaded gas.  I drive the car frequently, including high speeds on long trips to GNs and have never had any problems.

A friend, Frank Lindauer, also had a '49 on which he never had hardened exhaust valve seats installed.  We often convoyed together to GNs and elsewhere at the same high speeds and he never had any problems either. 

As far as I'm concerned it probably makes no difference on our cars, as it could be that even occasional high speed use, even hours at a time as in Frank's and my case, is not the equivalent of a car in daily use under all driving and weather conditions. 

[fishnjim]

In the US, it's not legal to use lead additive in autos.   It's permitted in other countries, etc.
The "substitutes" on the market are all based on alkali metals.
Unless you drive your classic daily or long distances, there's no wear issue to worry about.   
If you rebuild, they'll probably install hardened seats to go with the current valve meterials, which is the solution to seat wear.   
Lead, (TEL) tetraethyl lead was introduced and patented as an octane booster, not for valve wear.   The valve story came later.  Be aware, you get more fouling with TEL use in your motor.   

[Jon S]

The classic engines did not have hardened valve seats and Lead served for over a half a century as the lubricant to prevent damage. It's a crap shoot not to add an additive. I use additives in my pre-1974 cars as they are all original. JMHO

[David Greenburg]

But Amoco sold lead-free gas throughout the high compression era without any problems I am aware of; in fact it was a popular racing gas.

[wbdeford]

93 octane unleaded gas for 17 years, including the ethanol, in my '58 SDV and no issues.

[bcroe]

I drove my 60s cars very high miles and often above the speed limit.  There were plenty
of problem with the valves even with lead; it would get even worse without lead. 

I got fed up with those engines.  Now I drive 77 up engines with hardened valve seats,
valve rotators, electronic ignition, and probably better rings.  With unleaded they just
keep running CORRECTLY, unlike my 60s.  Bruce Roe

[55 cadi]

I don't remember what was exactly done but it was due to the lubrication that was in gas before and is not there now.

That is why we add stuff to it now for that reason.

I had it done about 25 years ago and yes I drove my classic as a daily driver, to and from work, out on weekends and out on weekdays after work, and it was a 66 mustang so it had high speeds on it as well,  so I had a lot of use on my car and was told back then that I should have it done, and this was I believe before all these additives came out to add in the lubrication.

Did it need it done??  Don't know, I was going by what the concensess at the time said to have done.

[jwjohnson86]

No issues with burning premium unleaded in my 1970 without any additives - then I just add my Stabil to a freshly filled tank when going into winter storage.  Lit right up last spring with first turn of the key after 5 months.

[cadman56]

I used only Marvel Mystery Oil mixed in with the gas and use Tropartic 10W30 engine oil year round.  I was told the 365's don't take to valve seat replacement well so never changed them.  Used all stock parts.  I drove my 56's hard.  I just loved the sound of the glass packs at 70 mph with my foot in it till it shiftwd up.  Never any smoke or rattles.  Drove them hard like this for many years.  Can't wait to get my 56 Seville on the road.

[walt chomosh #23510]

John,
  By 1965 the auto companies were already gearing up for the future and I suspect valves and seat were much more resistant then say a 1955. My 1964 Chevelle already had seatbelt fastening nuts welded although the car had no seatbelts for example. My machinist friends made a lot of money off of installing seats and valves but also tell me that a 65 really doesn't need them. One variable is the amount of driving you will be doing.....walt...Tulsa,ok

["Cadillac Kid" Greg Surfas 15364]

FWIW,
Cadillac Engineering knew well in advance about the pending removal of lead from motor fuel, and in anticipation, installed hardened valve seats in the 429 motors. Thus, no lead is needed.  I put over 100K on my 66 using unleaded with no ill effects.  The thing to remember is these motors had a compression ratio of 10:1, so 93 octane was needed for mine to avoid "knock".
Greg Surfas

[TJ Hopland]

I think the higher end makes always had less issues with this than the lower makes did.   I believe Cadillac always used high nickel castings which made them harder to start with.   It was your more common makes like Ford and Chev that really suffered because they were lower quality castings to start with.     

1966 for example Cadillac sold 200,000 cars,  Chev 2,000,000.   Lets say someone at Cadillac said lets put $0.05 more nickel in the blocks and skim it one more time for another 0.05 before we pour, no problem that is only going to cost $20,000 so we just ad $1 to the price of the car since we don't really have to compete with anyone,  Lincoln only sold 55,000 cars.     Now for chev that would cost them $200,000 and Ford was selling close to the same number of cars at the time.   

I used to have a neighbor that worked at a Ford engine plant and he said when they would build the Lincoln motors they would slow the line down and had a different QC list, blocks that didn't make it went into the Ford pile.   He said Lincoln didn't get any air bubbles or core shift.   On the Ford like there was a much wider tolerance.   He said everything was slower,  the pour was slower, they cooled longer, they got more time to inspect em,  everything.    I don't remember how many castings they would do in a day but on Lincoln day it was significantly fewer than when they were casting Fords.    I would imagine the same thing happened with GM and Cadillac,  they just spend a little more time on the Cad engines than they did say on a Chev.   

[savemy67]

Hello all,

Thomas Midgley was not only the guy that brought us Freon, he also brought us tetraethyl lead (TEL).  TEL is an organo-metal compound whose chemical formula is C8H20Pb.  This can be written differently to reflect the tetrahedral structure of the compound, which is an atom of lead (Pb) bonded to four ethyl groups (CH2CH3).

Chemistry aside, the number one reason TEL was added to gasoline starting in the early 1920s, was to increase the octane rating - and thus reduce engine knock - of cheap gasoline.  It was less costly to add TEL to gasoline than it was to try to refine and produce gas that would not allow engine knock.  As refined, gasoline does not contain TEL, it was added to refined gasoline until it was completely banned in the U.S. in the 1990s.

As a secondary effect, TEL's knock-eliminating properties also prevented exhaust valves from micro-welds due to engine knock - no knock, no micro-welds, less exhaust valve wear.  I am reasonably confident that TEL was originally never intended to be a valve "lubricant".  If your engine doesn't knock on unleaded gasoline, odds are your valves will wear as intended based on most driving conditions, except sustained high RPM driving.

I would be more concerned that a machine shop would cut into the water jacket of the cylinder head when installing hardened valve seats, than I would about valve seat recession.  Just one of many articles on TEL can be found here: http://www.unep.org/transport/pcfv/pdf/vsr-finaldraft.pdf.  The article is 29 pages including notes, and discusses valve seat recession in particular.

Respectfully submitted,
Christopher Winter