1. Aviation gas is NOT recommended for octane boost or valve protection. First, it is illegal to put av-gas in street vehicles without paying road taxes, both state and federal. Second, the additives and scavengers in the various types of av-gas are not the same as in gasoline formulated for street use. Your car might not start in the cold months of the year due to the lower Reid vapor pressure of av-gas and under certain circumstances use of av-gas could contribute to other engine operating problems including fouled plugs and/or plugged injectors, and excess combustion chamber deposits which raise the required octane number (RON) for your engine.
2. Rebuilding engines with hardened exhaust valves, seats, inserts is recommended when you NEED an engine rebuild. Do not rebuild just to have the engine retrofitted. Until you rebuild, use of an exhaust valve antiwear additive (EVA-A) is recommended. If you want hardened materials in an engine rebuild, you must specify this at the time you authorize the work your machine shop or dealer will not install hardened parts unless specifically instructed to do so. Rebuilding with hardened parts is more expensive, but recommended if your vehicle is used daily. (Some engine designs will not accommodate retrofitted parts, particularly exhaust valve seat inserts, and therefore cannot be modified.)
3. Will I experience exhaust valve failure on unleaded gas? A multitude of tests by EPA and industry clearly show the likelihood of such premature failure is high for engines designed to run on leaded gasoline.
4. Is excess octane bad for my engine? No, but it is a waste of money.
5. How do I know I'm getting enough octane? Your rule for how much octane your engine needs is the engine itself. If it knocks or pings, you need more octane. If left alone, the knocking will cause premature engine failure in that the explosion can blow a hole in the top of the piston, requiring a new engine. High octane causes gasoline to burn allowing it to create large volumes of gas to push the pistons down low octane allows gasoline to explode and very little gas is created. Therefore, much unburned fuel goes out as exhaust lowering your gas mileage, wasting your money, and increasing environmental pollutants.
6. How do I get increased octane? First try running only premium unleaded. Second, add a non-alcohol octane boost additive. Third, install a water injection unit. (alternative: have the compression ratio reduced and timing retarded so you can run on less octane this usually decreases performance but if you are just driving around at low speeds it may suit your needs, and is economical.)
7. What is the difference between low-lead and regular gasolines? When regular gasoline contained 1.1 gplg, the term 'low- lead' meant .2-.3 gplg. If your owner's manual specifies 'use regular or low-lead gas', the 'low-lead' means a minimum of .2 gplg.therefore. Remember, today's 'regular' gasoline is unleaded. If your owner's manual refers to 'regular or low-lead' gas, your engine was designed for leaded gasoline.
8. Which EVA-A is recommended? Several on the market will help reduce premature exhaust valve wear. Two primary products were tested by EPA and found to have positive results. These are Powershield by Lubrizol and Valvemaster by DuPont. The first is sodium based and can be used in vehicles with catalytic converters (important if you are using a late '70s car as your tow vehicle); the second is phosporus based and may not be used with catalytic converters. Make sure the product you choose clearly states that it is for "Exhaust Valve protection." Many products claim to replace lead, but are only octane enhancers.
9. Does my upper cylinder lubricant protect the exhaust valves? NO! Upper cylinder lubricants are light oils which burn at 400-F + . The temperature at the exhaust valves is 1600-F + consuming the upper cylinder lubricant before it reaches the exhaust valves. Upper cylinder lubricants are valid for the intake valves, cylinder walls and rings, but not for the exhaust valves or guides.
10. COMMENT in addition to the use of an EVA-As for specific exhaust valve protection, preventive maintenance is the best general engine life extender for all engines under all circumstances. As a guide, change oil at 3-4,000 miles (using a pre-oil change conditioner), and be sure to change oil and air filters. Change transmission fluid at 15,000 miles, plus filter (be sure pan is removed and drained as well). Change fuel filter as recommended by manufacturer or sooner (manufacturers' recommendations range from 5,000 miles to 30,000 miles check owner's manual) we recommend every 5,000 miles. Check all belts every six months. Keep engine in tune for improved performance, economy, and lower emissions.
Phone 1-520-622-2201 or Fax to 1-520-792-8501 or E-Mail isvpinfo@dakotacom.net
Last updated May 30, 1997
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