Oil change intervals

[tirod]

Originally Posted by Rick Parker

It's been mentioned here before: Each time the engine temprature warms up and cools it passes through the "Dew Point" and moisture is created.

That's not quite true.

First, there has to be water present in some form to be able to condense. Once oil is heated beyond 212, water boils off, and the vapor passes out of the engine thru the PCV or valve cover breathers. It doesn't take long to boil off the few grams of water that were present, and once it shuts down, only a minor residue can form. It doesn't magically form from oil molecules.

What actually happens is keeping the car stored in an unheated area that allows it to warm during the day, and cool at night. Then the cooling metal of the engine and pan condenses what moisture vapor might have gotten back in - again, thru the crankcase ventilation system, which isn't configured to pass fresh outside air thru it when the engine isn't operating. Given enough cycles, some moisture may build up.

As will condensation inside your gas tank. Do you change your gas - regardless - every three months of storage? Secondly, why let the car sit idly by and slowly rot with inactivity? Tires age, hoses oxidize, the alcohol laced fuel attacks the rubber lining in the older standard fuel lines (called AN by some,) and water condensation attacks and corrodes the metal in tanks and lines, too.

If it's so important to change the oil every 300 miles to protect the bearings, why ignore the fuel system and it's much more likely catastrophic failure? If you fail to plan a cycle of periodic operation, you plan to fail. If acid sludge could build up in nearly fresh oil with 300 miles on it, how much more that gas tank full of fuel laced with water, alcohol, and all the corrosive additives? It's an industry standard now, fuel goes bad in 90 days.

Since changing the oil every 300 miles is the standard, when you park it - drain it out and leave it out. Refill when you get back to good weather. Same with the gas, drain it and run it dry. Gelled, corrosive fuel in the carb or injectors is worse than some lightly etched bearings.

BTW, you do use dry nitrogen in the tires, and deflate them once the car is on jackstands, right? Don't forget to seal the garage and purge it with nitrogen, too. Really saves on the vinyl upholstery and paint continuously oxidizing, it's museum standard.

And some of you were worried about the oil? Waste of money.