[user removed]

1. Grille blocks do increase engine compartment temperatures, relative to a non blocked grille. Higher sustained tempertures will cause gradual degradation of engine compartment components. Is the degradation significant? It depends on the climate and peak compartment temperatures. One reason I left the clutch fan on the Ranger was it increases engagement depending on the temp of coolant passing through the radiator as well as the fact that there are several other openings in the front of the truck that are not blocked. No problems with original radiator and coolant hoses and no loss of coolant at 16 years and 130 k miles, so in my case I'll keep the grille block.

2. Thinner lubricants actually flow faster and keep friction surfaces cooler due to increased flow volume. Also thinner lubricants require less energy to push through the lubrication passageways. Also, decades ago Ford reduced the maximum oil pressure to 35PSI by weakening the oil pressure relief valve spring tension. It was responsible for a .5 MPG increase in fuel mileage and after decades of seeing many modern engines hitting 3-400 K miles I can't agree with the rationale that you are increasing friction. Tolerances have been significantly reduced in the same time period. Nissan has used 4 different stock piston sizes as well as main and rod bearings. In other words there are 4 different sizes from the factory. They picked the sizes depending on the finsihed tolerances of the bores and main and con rod journals.

Bottom line is with modern manufacturing technology, thinner oils are part of the combination of improvements that have seen engine life quadruple in 50 years. The much higher SAE oil grades available today are another part of the total systematic improvements. I totally disagree with statement number two.

3. EOC will cause increased stress on some components. Catalytic converters suffer from increased heat cooling cycles. Sentra stopped using EOC when he found it was causing his emissions to increase dramatcially, to the point where testing showed long term effects (he is certainly free to add info, this is what I read from his posts). I don't believe EOC overstresses cooling systems. Obviously if you EOC enough to drain your battery if will shorten battery life, and if you use the starter more frequently, then, in my opinion you will reduce it's life expectancy. Repeated heat-cool events, beyond what is considered normal could also increase the accumulation of EGR-PCV deposits.

As far as higher temperatures causing metal deterioration, it must be understood that to get to that point you would have to be far in excess of designed operational temperatures, and if this was the case, then you would see significantly greater longevity of engines in colder climates. I think the opposite is true. in my opinion extremes of operational temperature are the principle cause of premature engine failure.

I don't use EOC myself.

regards Mech