GENERAL CORVETTE DISCUSSION

The following courtesy of HAGGERTY:

So you’ve got a vintage car? Welcome to the club! In our quest to keep these pieces of automotive history alive, we’ve learned a few things about keeping old cars on the road in the modern age. That extends to helping you keep your vintage iron in top running condition. To make sure you’re ready for the road—and stay that way—we’ve put together this FAQ.

Here, you will learn:
> What to know about using modern fuel in older vehicles

> How to maintain your vehicle’s oil, including the use of zinc additives
> How to keep your vehicle’s battery in top operating condition
> What items to travel with in your vehicle
> How to make sure your tires are ready for the road
> Ongoing care for your four-wheeled friend
> What to do in case of emergency
> Tips for long-term storage of your vehicle GASOLINE: There are five basic facts you need to know about today’s gasoline and how it can affect the proper operation of your vintage car:

> You should have zero tolerance for fuel leaks
> Ethanol in gasoline can cause problems in cars built before the 1990s
> Allowing gasoline to sit is not good
> Don’t buy lead replacements; do buy premium gas
> Fuel pumps die
> Have zero tolerance for fuel leaks:

Gasoline isn’t like oil or antifreeze. It’s not OK to have a few drops of gas beneath the car as long as they don’t get bigger. If you smell gas, you need to find the leak and fix it before you drive the car again. Often, it’s just the end of a section of rubber fuel line that can, if necessary, be trimmed and re-clamped. But if it’s from a rotted metal fuel line, or from the rusted seam of a gas tank, then unfortunately you have some pain and expense ahead of you. Better that than having your car do an impression of The Towering Inferno.

Ethanol in gas is a problem: Depending on the state or region, every gallon of gas may contain 10 percent to 15 percent of government-mandated ethanol, an alcohol that is derived mostly from corn. There is little good about ethanol in gasoline. The most common gasoline/ethanol blend is E10. This refers to a federally mandated blend of gasoline that has 10 percent ethanol in it and is sold at most gas stations around the country. E15, which contains 15 percent ethanol, is found in some areas. “Ethanol is hygroscopic, meaning that it absorbs water,” states Paul Millner, a retired refinery engineer who worked at Chevron for 38 years. “When ethanol is present in gasoline, a corrosive mixture of water and ethanol can accumulate at the bottom of the gas tank, as the water/ethanol drops out of solution with gasoline at lower temperatures.” Millner explains that the corrosion problems are exacerbated in vintage cars that aren’t driven frequently, often have steel fuel tanks, and have tanks that are poorly sealed, either by design or due to degraded or missing emissions system components. Moist air enters the tank, the water gets absorbed by the ethanol in the gas, and an ethanol/water solution separates out and accumulates at the bottom of the tank. The water rusts the tanks, and a combination of water and corrosion products cause rough engine operation due to plugged filters, injectors, or carburetors.

Ethanol also attacks rubber fuel lines, seals, gaskets, and older sealant material as well as other soft fuel-system parts such as carburetor floats. If you haven’t replaced your original rubber fuel lines with modern ethanol-resistant ones, you should. If the lines feel soft and spongy when you squeeze them, you should have them replaced now.

Note: Gasoline refiners rely on ethanol’s octane boost to achieve the advertised gasoline octane. As ethanol is lost with water separation, the octane of the gasoline arriving at the engine is reduced.

You should seek out ethanol-free gas, which often will be labeled as “recreational gas” or “rec gas” because it is intended for use in recreational/marine engines that can be damaged by ethanol found in other gas blends. Availability varies from state to state. Websites such as Pure-Gas.org and BuyRealGas.com assist in locating ethanol-free fuel.

Don’t allow gasoline to sit too long: Before a car is stored for months, it’s wise to add fuel stabilizer such as Stabil or Sea Foam to the tank and then fill it with gas. However, doing so only prevents the gasoline from going “sour.” It doesn’t alter ethanol’s hygroscopic properties or cause water that has already formed in the gas to magically dissolve. Adding a different alcohol, isopropanol (also known as isopropyl alcohol), makes the water soluble in gasoline when used in a ratio of two percent by volume of isopropanol to gas. This helps carry it through the combustion process. “Methanol also has this property, but methanol should be avoided due to its propensity to attack soft metals in the fuel system,” says Millner. As a reference point, Chrysler forbids use of methanol-containing fuel additives in its products. As a result, it is important to read the label. For example, HEET brand fuel additive comes in both methanol and isopropanol formulations. Only buy and use the isopropanol version.

It’s a good idea to completely fill the tank before storage, as this eliminates the air space where condensation can occur as exterior temperatures fluctuate. Take this consideration as a justification to use the entire tankful on an extended pleasure drive when you pull the car out of storage.

While gasoline aging rarely becomes an issue over the course of two to three months, letting gas sit longer can have undesirable consequences. If you open up the gas tank and catch a whiff of that “varnish” smell, the gas will need to be drained. As gasoline sits longer, the fuel will leave behind a gummy residue that will need to be removed professionally either by scraping or by using chemicals.

Motor gasoline (also known as “mogas” for cars and trucks, as opposed to aviation gasoline, known as “avgas,” for airplanes) contains olefins, a relatively less expensive, moderately good octane component. Olefins, however, are not time stable. “Catalyzed by the presence of metal such as that of your car’s fuel tank and lines, the olefin molecules connect together, or polymerize,” says Millner. “The polymerization first creates goo in the form of gums and varnish and then eventually turns into a solid.” Stabil can slow this process by inhibiting the metal surfaces, but it doesn’t completely stop it. Since most older vehicles have metal rather than plastic tanks, this is a common problem.

If you buy a car that has had a long sit, you should never just add gas to the tank and try to start it. Instead, you should perform a back-to-front clean out of the fuel system. First, inspect the tank and fuel pickup tube. Next, change every rubber fuel hose as well as the fuel filter, and then open up the carburetor to check for gum or sediment in the float bowl. If it’s a fuel-injected car, getting the injectors cleaned is good insurance against running problems.

Don’t buy lead replacements; do buy premium gas: Your valves don’t need any more help than a higher grade of gasoline would provide. So-called “lead replacements” are generally ineffective in boosting octane or protecting the valvetrain. Conventional wisdom says that the lead in leaded gasoline protected valve seats, stems, and guides, which many owners of pre-1976 engines address with lead-replacement additives. Millner says these efforts are misguided. “In the combustion process, lead becomes lead oxide, or in the presence of lead scavengers in the fuel-additive package, lead oxybromide,” he explains. “Neither of these lead salts are lubricants but are rather more like abrasives.” It is true that receding valve seats were recognized as an issue with the phaseout of lead in gasoline in the 1980s and early 1990s, but that was not due to the absence of lead. The Environmental Protection Administration’s mandated shift in gasoline-octane-reporting schemes added to the confusion.

“The bottom line is that lead didn’t prevent valve problems—the changes in how gasoline-octane ratings were calculated did,” states Millner. With the phaseout phaseout of lead, octane ratings became much more difficult and costly for gasoline blenders to achieve. At the same time, the industry was successful in getting the EPA to recognize statistical methods for octane verification, since results from individual octane tests vary significantly (as much as one octane number) around a statistical norm. The bottom line is that the *delivered* gasoline octane declined to being much closer to the number on the pump. For instance, in 1970, a gasoline rated at 92 Research (~today’s 87 (R+M)/2) might actually have two or three numbers of octane giveaway, testing at 94 to 95 octane. By 1990, with the cost of delivering octane having escalated, and as permitted by the EPA’s statistical methods, the octane giveaway was likely to be closer to just a tenth or two of octane number. It was this decline in *delivered* octane, say from 95 to 92 (while the number on the pump didn’t change from 92, or 87 in the new system) that affected engine performance and valve wear.

When it’s time for a valve job, by all means elect hardened valve seats, because they will last longer and won’t be damaged when you aren’t able to use high-octane gas. “There’s nothing in a pint or two of ‘lead-replacement’ tonic that will either affect valvetrain longevity or gasoline octane,” says Millner. “To noticeably boost octane with such a small quantity, the additive would have to include lead (very toxic) or methyl-manganese (tough on spark plugs and catalysts).” As a side benefit, premium gasoline often contains fewer olefins, and so is less likely to degrade over time.

Fuel pumps die: Carbureted cars usually have a low-pressure mechanical fuel pump with a rubber diaphragm. With age, the rubber loses its elasticity. This can first manifest itself in the car being very difficult to start after sitting, as the pump has trouble filling the fuel lines and the float bowl in the carburetor. Eventually the pump stops working completely. Electric fuel pumps usually fail in a more binary way—they either work or they don’t. Sometimes pumps get clogged by rust from the gas tank that finds its way into the rest of the fuel system. In either case, the symptom is a car that starts, but dies a few seconds later. The fuel pump is usually the culprit.

Cars with internal fuel pumps in the fuel tank rely on the fuel to cool the pump. If you normally keep the tank one-quarter full or less (which is understandable perhaps for a car not driven often), you have insufficient fuel to cool the pump. As the pump ages, it becomes more susceptible to cooling-related failure. So keep the tank at least half full.

OIL

Let’s be clear: Oil is the lifeblood of any engine. And just as there are different blood types, so are there different oils for different engines, uses, and climatic conditions. So while there’s no “one-oil-fits-all” answer, there are some pretty general guidelines you can follow. Here are some considerations on lubricating oil for vintage cars:
> Stick with conventional oil versus synthetics
> Change your vehicle’s oil annually
> Check your oil level before you drive
> Choose the correct viscosity of motor oil
> Choose the zinc level of your oil carefully
> Consider alternative additives

Stick with conventional oil versus synthetics: If the manufacturer didn’t originally specify synthetic oil, you can stick with conventional oils to avoid problems. You could consider semi-synthetic oils, but the synthetic content can lead to seal leakage on older cars. The benefits of synthetics include very high operating temperatures and long life between changes, benefits that aren't generally realized in older cars that were designed for lower operating temperatures. Classic car oil generally loses its lubrication quality from time-related oxidation and engine-blowby water and acids long before the recommended mileage is reached. 

Change your vehicle’s oil annually (at minimum):  Most vintage cars won’t reach the mileage recommendations for oil changes, so change your oil and oil filter at least once a year. Motor oils contain antioxidation additives; when you open the container, however, oxidation begins. Once the engine is started, the act of combustion contaminates the oil with moisture and combustion-byproduct acids. This underlies the lubricant maker’s suggestion to change oil at least every four months, no matter how many miles are driven.

Change your oil right before you store your car at the end of the driving season. This ensures that the oil is free of moisture and acids, which you don’t want sitting in the engine over the storage period. Better to drain that out and replace with fresh oil, preferably with an anticorrosion additive.

Choose the correct viscosity of motor oil:  there’s a lot to consider when choosing motor oil viscosity, and nothing can replace the specialized knowledge of your make's car club, so consider joining it. Here are some general observations to get you started.

Begin by researching what the original viscosity recommendation was. Perhaps you don't have the original motorist's information booklet that came with your car, but someone has likely uploaded it online. Start there.

Single-grade oils may still be the best choice for pre-World-War-II design engines, especially if the crankshaft has roller bearings. Bearing metallurgy may be incompatible with modern oil detergents. Do your research!

Our classic cars aren't spring chickens, and engine wear is to be expected. The modern multi-viscosity oils are a great option, since the oil is thicker at operating temperature than a corresponding single-weight oil. This improves oil pressure and reduces oil being pumped past the rings, thus reducing spark-plug fouling and oil consumption. Let's explain the numbers: When we refer to an oil as a 20W-50, that means at room temperature, it's a 20-weight motor oil, which is important for winter (hence the “W”) starting conditions. However, through the choice of blending components with a high viscosity index and addition of viscosity-index improvers, the multi-viscosity 20W-50 oil thins much less with temperature than a straight 20 weight would. The “50” in the 20W-50 grade tells us that at engine operating temperature, around 200 degrees, this specially blended oil has the same high-temperature viscosity that a 50-weight oil would have. The viscosity index (VI) is the measure of how little or how much the oil thins with increased temperature. Choosing or additizing to high VI oils gives us the best of both worlds: a light oil when the engine is cold and oil pumping is more difficult, but a thicker protective oil at engine operating temperature. You may have selected a 20W-40 in the 1960s for your then-recent Lincoln; today, that senior vehicle might well favor a 20W-50 or even 20W-60. 

Check your oil level before you drive: We’re not in favor of adding oil every time the level changes minutely, but at least top up when the oil level drops by a half-quart. If you’ve been driving mostly around town, the odds are that some combustion-byproduct water has condensed in the oil supply. Don’t be surprised if you have to add some after a freeway run that boils off that water.

Asking for recommendations on which oil to use is like bringing up politics at a family Thanksgiving: You’ll hear a lot of opinions, and some strongly held ones. If you don’t have a trusted local mechanic you can consult, try an online forum for your model of car and be specific about the climate where you live.

Choose the zinc level of your oil carefully: Modern oils do require modification to meet the needs of older engines. One alternative is to select a diesel-spec oil such as Shell Rotella with ZDDP, but be sure to check the manufacturer’s safety-data sheet for the zinc level. Zinc dialkyldithiophosphate (ZDDP) is the most commonly used antiwear additive in motor oils, expressed on the spec sheet either as a percentage or in parts per million (ppm). The ZDDP compound forms a protective layer on steel in the presence of pressure and temperature, preventing metal-to-metal contact. In classic car engines, this is most important to mitigate sliding wear at the tappets in the valvetrain. In more modern engines, roller tappets mitigate this wear point. The traditional zinc additive isn’t very friendly to catalytic converters, so modern engine oils have dramatically reduced requirements and levels.

You’ll definitely want these additives to protect the flat tappets—or an alternative (see below)—for almost all engines used before catalytic converters became mandatory in 1976. Look for the specialty oils that contain them. A few mass-market oil brands now offer “racing” lines of oil that are sold in most chain auto-parts stores, including Valvoline VR1 and Mobil 1 Racing. These racing oils have elevated levels of ZDDP of around 1100-1300 ppm and are designed to capture the market for older vehicles. The racing designation is meant to separate these oils from oils that are compatible with modern road cars and have zinc levels closer to 600-700 ppm. The high-zinc oils should not be used in anything modern to avoid damage to the catalytic converter. Again, some research into the ZDDP content of each oil is a good idea, with a comparison of that to the requirements of your car’s engine, since different cars need different amounts of zinc. For instance, a 1966 MGB running a stock camshaft will be happy on the 1300 ppm of ZDDP in common brands like Valvoline VR1, but it doesn’t need as much ZDDP as a 1966 Chevy Chevelle quarter-miler running a racing camshaft. The race camshaft will benefit from the 2000-2400 ppm of zinc in, say, Red Line Racing Oil, to prevent metal-to-metal contact between the lifter and cam face.

However, you shouldn’t assume that more zinc is always better. Don’t blindly choose oil with a really high content of ZDDP or “top off” a high-zinc oil by using even more ZDDP additives that are sold separately by companies such as ZDDPPlus or Rev X. Too much zinc in the oil causes bearing corrosion, sludging, and plug-fouling problems. This won’t be an issue if you’re changing oil between race weekends, but it might be a problem if you drive the car once a month and change the oil only once a year. In other words, what kind of car you drive and how often you drive it should be your guide on what kind of ZDDP content to seek in your oil.

Consider alternative additives: Many “mechanic-in-a-can” solutions are offered online and at the auto-parts store; some are formulations that have been around for decades. Even so, many offer no real advantage, being composed of light-weight motor oil, fragrance, and coloring. There are some additive packages that are derived from more modern lubrication science, but it’s always wise to investigate the science behind any offering. One additive worth your investigation is ASL CamGuard, which is touted to reduce wear, control corrosion, protect highly loaded surfaces such as tappet faces, and extend the life of engine seals. The formulation comes out of work done at Exxon but was deemed by management as being too expensive for inclusion in its motor oils. For our classic cars and their special needs, however, there are some real advantages. Take a look at the website (https://aslcamguard.com/) and make special note of the tech data there. Those who have their engines on oil analysis report reduced wear of metals, and that is promising. It may be possible to sidestep choosing the right level of zinc in your motor oil by including this alternative instead.