Quote:
Originally Posted by cdavisdb
. . . From what I've read, the real danger is small quantities of ethanol in the Rec90, like one percent or less, so that a minimal amount of water will produce phase separation. That can happen multiple times and the sludge build up in your tank. I feel the need for a testor that will measure small quantities of alcohol. , , ,
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If you approach the Rec 90 vs. E10 decision from a "consequence of failure" standpoint, I think it becomes a simple decision IF Rec90 is readily available in your area:
Rec 90: Probably safe to assume that some Rec90 will either have some water in it as purchased or be contaminated with ethanol by putting Rec90 gas in tanker trucks that had carried E10 and were not completely drained first. Worst case scenario is repetitive sludge build up from continuous use of low % ethanol laced Rec90, where the corrosive sludge overloads both the Racor and on-engine filters and possibly kills the HP fuel pump, and worst case, some fuel injectors. The E-TEC HP pump is ~$150, but the injectors are $400 ea., so it could get expensive in a hurry if it were to kill injectors. At least the Rec90 octane level would not be affected.
Preventative Maintenance required: Test all fuel for ethanol contamination before filling tank, and check Racor frequently for water/sludge and drain it out before it overloads filter.
E10: Worst case scenario is somehow getting enough water in the tank, via vent fitting, leaking O-ring on fill cap, leaks around sending unit gasket, or corroded holes in tank, to phase separate ALL the ethanol, dropping octane level from 87 to ~83-84 octane! The larger E-TECs (3.3-3.4L 90 degree V6 motors and all the new G2 models) have knock sensors that will detect the detonation from the bad fuel and display a "Knock Detected" warning on the I-Command gage if the EMM is not able to retard timing or enrich mixture enough to eliminate it, but the smaller E-TECs (60 degree V-6 and V-4's, and all I-3 and I-2 models) do NOT have knock sensors, so first sign of low octane fuel will probably be when detonation blows a hole in a piston! Fixing this will cost much more than replacing a fuel pump and/or some injectors! With a 4-stroke motor, you MAY be lucky enough to be able to hear the valves rattling and throttle back before it fails a piston, but ANY 2-stroke motor without a knock sensor is especially vulnerable to detonation because there are no valves to rattle!
Preventative Maintenance required: Test all fuel to insure ethanol content does not exceed 10%. Inspect fuel tank to insure no corrosion holes, and inspect sending unit gasket, gas filler cap O rings and vent hose routing and fitting to insure NO water can find it's way into the tank. Check Racor frequently for water or phase separated water/ethanol. If running E10 gas, you should expect to NEVER find any water in filter bowl. If you DO find water/ethanol sludge, it's a big red flag that you may have a load of low octane fuel, so you may want to drain tank and burn it in your truck, lawnmower, etc., or at the very least add some octane booster or top off the tank with some premium 92+ octane E-10 gas!
Although this isn't a real scientific risk analysis where you'd have to multiply (Probability of Occurrence)x(Cost of Occurrence) to quantify potential costs of a worst-case failure of each option, I've concluded that Rec90 is fundamentally lower risk because loss of octane is not an issue. I know the Racor will trap water and/or ethanol sludge and it's easy to monitor that. Conversely, I can visualize situations where significant amounts of water could get into a tank of E10 without my knowledge, and the resulting octane loss could quickly destroy any engine without a knock sensor!