VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Zinc and Ethanol "Cure" additives

Today at a local car show, while discussing my '34 knock problem (see other post), a friend who is a Chevy mechanic (35 years) got to talking about gasoline additives needed due to fuel changes mandated by Washington.

We talked (rather I listened) about the problems with ethanol in our older engines especially if they sit around without being ran a lot. I was not unaware of problems but did not realize how bad they can be ranging from increased vapor lock to floats being eaten away, etc. He also is thinks it important to add a zinc additive to avoid wear problems with the cam shaft/push rods.

I use Stabil's additive for ethanol in my two cycle engines, lawn tractors, and just started adding it to my 3 older cars. I have not used zinc yet.

I'm wondering what some of you think or know about these issues and if you would like to offer some suggestions or products to avoid problems. Thanks ahead for any replies!

I just had an engine rebuilt and my rebuilder added a zinc additive to the oil. It is important to use a zinc additive, (ZDDP, etc) for rebuilt flat tappet engines, as they need the lubricating properties for the camshafts. Modern oils have eliminated zinc additives to increase the lifespans of catalytic converters. GM Engine oil supplement and some of the Valvoline racing oil have increased zinc but wouldn't recommend the racing oil for cruising.
Ethanol gas is an absolute evil that's been foisted on an unknowing public IMHO. It absorbs moisture (hydroscopic), is more acetic, and water will separate out of fuel after sitting a little as 30 days. One can maintain a full tank to lessen this event. I've run Startron Starbrite which is a fuel enzyme additive which keeps the water from separating out of the fuel. Had mixed results and am running non ethanol premium fuel available in the summer here in New England. Recently I had a sticking float/float valve in an otherwise new fuel system so I'm blaming the gas. Check www.pure-gas.org for a list of stations in the US and Canada which sell non ethanol gas. Good luck.

I totally agree with that! Ethanol is some really bad stuff!

I have also been useing Stabil's for the last year or so.The tanks is still quite new.Whats the thoughts about this additive???

I hope that styeline51 does not take the following personally as I feel that he is just reciting what he has heard or read elsewhere. Zinc has not been eliminated from SM motor oil! It has been reduced from the level in SL motor oil to approximately the same level as the 1950s. I don't have a dog in the fight as I don't and never have worked for an oil company, just trying to set the record straight and not perpetuate a misconception.

Not an expert, but I keep only a couple of gal. of gas in the tank at one time. That way I am always adding just enough gas for each drive. It freshens up the gas. No problem with old gas. I also put in a small amount of stp gas additive to soak up water and add a little marvel mistery oil for those old valves.

Yes it is.........


Well, all I can say is that we have had stuck valves and stuck float valves for as long as I can reckon, and Fuel and oil additives make a lot of money for those that sell them.....

With the information overflow that we have now I guess we will hear about every stuck valve, every knocking rod and ever carb that floods and leaks a few drops of gasoline onto the manifolds that happens to our vintage engines, and ever miss and sputter that happens. It does seem that locally we have an extra run of stuck valves in machine shop worked over 235 heads. I had a talk with a local machine shop owners that does a large percentage of the head and valve work. He was complaining about having several stuck valves in 235 heads with only a few hundred miles on an overhaul. He did admit that he was replacing and reaming the valve guides to modern Chevrolet SB specs. I gave him the correct specs for a 235, he said 'Wow! that is a lot looser than I thought they should be. I explained the differences in the overhead lubricating systems and operating temps. on the pre-1963 sixes. (The later 230, 250, engines employ virtually the same overhead oiling and valve rocker systems as the SB V/8 engines) He has had almost no valve sticking in the recent head overhauls, in fact he has noticed that with original spec valves that the clearances in the valve guides show that most of the heads require no new valve guides. As for the sticking floats many are prone to blame the new Vitron needle valves when most of the problems is crud and rust getting into the carb inlets. But you don't need to believe me, after all it is your money and your engines.

I have found a fairly good gasoline stabilizer. It is PRI-G We have found that gasoline treated with PRI- G can be stored in small engine fuel tanks for over three months without the gasoline gumming up. PRI-G does not keep the fuel tanks from rusting from condensation forming in the steel fuel tanks. That continues to be a modern gasoline problem. how about getting a new plastic tank and new gas lines? Whatever.....

All 10W-30 oils have zinc in them. Just the amount has been reduced. If a new cam and lifters are insalled I would add a zinc aditive. The valve train load is so light on the old 6 Cyl. engines any additional zinc is unnecessry after the brak-in period. When your 1934 was new there was NO zinc in the oil and they never wore out the cam lobes.

We have had ethanol gas in this area for the last 20 years. I have never had a probblem with it other than it does evaporate quickly.
I do not use alead additive in any of my cars and there again older cars had lower tension valve spring which is easier on valve seats. As a matter of fact lead additives do not even contain lead. Its just another was to suck money out of your pocket.

No offense taken Chipper. I stand corrected. I meant the zinc levels were reduced.
For those who refuse to believe the evils of Ethanol, take a baby food jar, fill it half full of E-crap gas, put the lid on, and let it sit.
You will see the water separate out. That's what sits in your tank if left untreated.